I recently saw a post detailing how a team won inspite of the fact that a teammate of theirs intentionally fed 46 times. I felt that this guy really could've used a guide on how to professionally feed in order to ensure his team lost.

For the most part, people don't know if they're gonna feed before hero selection. However, if you do, you need to pick the right heroes.

• Io: His low health combined with his set of skills that allows him and a teammate to teleport anywhere are ideal for feeding. Relocating that ♥♥♥♥♥♥ to the enemy fountain helps inflict unintentional abandons.
  
• Nature's Prophet: His Teleportation allows for more frequent feeds in addition to his Sprout which will allow you to strategically trap a teammate. Even his Nature's Call can provide some extra cash for the enemy.
  
• Faceless Void: A well placed Chrononosphere can help save the enemy from a gank.
  
• Spirit Breaker: Charge of Darkness in then do nothing, has the drawback of providing some vision on the enemy.
  
• Leshrac: Because even when you're to play him normally, you're probably still gonna feed.

Now lets say you didn't know you were gonna feed before hero selection. You still can throw the game if you do it right. This means building the right items on your hero.

• Flying Courier: Buy and then feed it to the enemies.
  
• Observer Ward: Let the enemy see you place it then provide them Sentry Ward so they can deny it to get more gold.
  
• Force Staff/Heaven's Halberd: Allows you to take your teammate out of position, ensuring more feeding.
  
• Armlet of Mordiggian: Allows for faster health drain.
  
• Mask of Madness: For that extra jolt of speed and makes you squishy.
  
• Blink Dagger: More speed for that feed.
  
• Drum of Endurance: More feed and speed. Too much health boost, not enough speed, just use the extra gold for spelling out curse words with wards.
  
• Tome of Knowledge: Give your enemies extra experience.
  
• Bottle: Drop it like it's hot!
  
• Gem of True Sight: Give that enemy some free vision, when needed.

In terms of gameplay, you do not just run around middle lane and feed. This only allows one player to get fat. You want to go top and bottom lane, and even alert the other team to your incoming presence and intention. Communication is important, for the other team. You gotta let them know when your team is going to Roshan or is in smoke or all rotating to another location. Wait, who am I kidding, no one ever uses the ♥♥♥♥♥♥♥ smoke.

When you are properly feeding, you need to hit the enemy before letting them slay you. This may be counter intuitive but I have avoided being punished from feeding many times by hitting the enemy before dying. That way it looks like you tried to fight, it makes a harder case for the intentional to stick.

In some situations you will need to feed harder than other times. The other team is just so ♥♥♥♥♥♥♥ bad that the 20 kills you fed them just aren't helping. This is when you send in the army of couriers. This provides much needed gold for the enemy. Make sure the enemy is supplied with gems if they need it and make sure you are distracting your teammates with insults and intercepting their courier.

With a little practice and effort, you will make those teammates rue the day they rightfully called you a noob.

Edit: Apparently, I can't even make a comprehensive guide on how to feed. I see some great hero recommendations and some great strategies so I'm gonna copypaste integrate that below.

• Tiny: Toss your teammates into danger.
  
• Tusk: Do you wanna build a snowman? Come on let's go get slayed!
  
• Outworld Devourer/Shadow Demon: They'll never escape that enemy gank thanks to that disable.
  
• Chen: Teleport them back to base using Test of Faith, it'll definitely test their faith in having patience.
  
• Kunkka: Cast X Marks the Spot on teleporting teammates and watch the confusion and rage unfold.
  
• Pudge: Pull your teammates over to the other side of the river and be sure to body block, or trap them on a cliff.
  
• Vengeful Spirit: Put yourself into position to be ganked then Nether Swap a teammate and watch them get ganked instead. Be sure not to level up the aura.
  
• Keeper of the Light: Recall that ♥♥♥♥♥♥ to commit suicide with you.
  
• Earthshaker: Block your ♥♥♥♥♥♥♥ teammates from escaping with a well placed Fissure; a great pick up against already blinked teammates like Queen of Pain.
  
• Earth Spirit: Push/pull teammates into enemies/onto cliffs. Buy a scepter for bonus points! And really, you are just as bad with him as you are with Leshrac so even when you're trying, you're dying.
  
• Oracle: If you have enemies like Phantom Assassin, Oracle is a great pick. When you see them jump on your teammate, quickly cast Purifying flames followed by Fate's Edict on the teammate.
  
• Winter Wyvern: Stop! In the name of hate before they break your heart.
  
• Naga Siren: If you have teammates like Enigma, you can ruin their ultimates with your Song of the Siren.
  
• Legion Commander: Die in Duel every time it's up. Your new ingame goal should be how much damage you can feed to the other team.
  
• Lone Druid: Fill up that bear with some couriers or wards or a gem and make a special delivery to the enemy. Don't forget to let the enemy know that he's friendly and comes bearing presents.
  
• Morphling: Go middle lane and Morph into full agility.
  
• Terrorblade: Get low health and swap them full with a teammate using Sunder.
  
• Clockwerk: Use Power Cogs to block/trap a teammate, making both of you an easy target.
  
• Tinker: With Rearm, you dont have a cooldown on teleport and can feed as soon as you respawn. As a bonus, you can also steal farm on every lane with March of the Machines.
  
• Bane: His Nightmare is excellent for disabling a teammate, can also be use to deny already safe but dying teammates, making them one step closer to rage quitting.
  
• Crystal Maiden: Probably the squishiest hero, try activating Taunt: Beautiful Snowangel when you're about to feed. Be sure to disable auto attack.
  
• Omniknight: Repelling the enemies during a gank is always a quick way to get some lovely attention from all your teammates. You can also spam Purification to steal farm from your carry.
  
• Underlord: Teleporting multiple ♥♥♥♥♥♥♥ to enemy territory using Dark Rift and commit mass suicide.
  
• Arc Warden: Double the feeding with your Tempest Double.
  
• Techies: Just picking him will inflict massive damage on the team psyche. Then steal farm with your mines and it's a recipe for starving and frustrating the carry. Apparently, placing mines at the jungle creeps can block the camp.

• Divine Rapier: Does the enemy have someone who actually looks competent? Make him fatter than Pudge on Thanksgiving Day by feeding him the rapier. Could end up throwing the game in your team's favor so use with caution.
  
• Ethereal Blade: Cast Ether Blast on a teammate to make them squishy against magical damage if you have enemies like Zeus, or save the enemy from physical damage if you have teammates like Troll Warlord.
  
• Hand of Midas: If you have no experience/gold, the enemy benefits less from killing you every time. This allows your feed to stay relevant even till the mid-late game.
  
• Eul's Scepter of Divinity: Save the enemy from that overpowered ultimates.
  
• Necronomicon: When the enemy needs that extra boost of gold.
  
• Aegis of the Immortal: If your team is able to Roshan, make sure you're there to snag it. Guaranteed to make the Ursa on your team curse in russian.

Laugh annoyingly into the mic, ask your team to commend you for ending the game quick, and tell them to relax because it's just a game. The chat wheel is also a fun way to be passive aggressive. Spamming well played! after every death is a must. You can also annoy them by pausing the game. Adding players in your friendlist is a possibility if they let you, there you can spam voice chat and gift them common items with mean inscriptions. It's also a good way to laugh at their Matchmaking Rating if its lower than yours or call them a tryhard gaming nerd if its higher.