So you can use the default character but personally I prefer one of the workshop c-o-c-k vore agents.
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=3203291239
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=3200123709
These two are my go to for gay sex, however for this guide I'll be using the playable Gruff as I'm a big fan of fuzzy guys with red eyes~

Now that you have a guy selected you'll want to play the game. There are no male c-u-m dumps in the first level so you will need to get through that first. I would recommend heading left as you leave the elevator room, there is a window above the breeding stand that you can go through to get to the shark boss quicker. However when doing this be sure to keep your fat balls as empty as possible because coming back through the small gap will be a challenge if you even have one churning preything in there.

Now that the shark boss is reduced to a c-u-m stain somewhere you will have unlocked the second level, The Warehouse!
Now that you're in the level you have two close victims you can bloat with thick seed. For the better angle I would recommend heading up the stacked boxes on the right side of the opposing wall from where you start. Be sure to grab a passing by guard (or anyone) to stuff down your shaft so you can really fill the stomach of your male partner. Head into the vent and you will spy a horned up fuzz ball ready for a good stuffing~ >:3
Be sure to fill up right in-front of your c-u-m dump for maximum skill points.

So now properly filling your partner comes with a little finesse. From personal experience, I've found out that almost fully pulling out and then fully thrusting back in a few times will cause your pressurised fire hose to dump gallons of freshly churned seed into the dump spot.









































(Partner after stuffing)^

Now that you have a lovely bloated Gruff they will serve you for the remainder of the mission! They move and hide full condoms that you have disposed of and watch as you churn more preythings into seed.

Or you can just shove them down your shaft too... If you're into the whole cruel pred stuff and want more c-u-m to hide when you move through the level! :3