Give me on of the following +rep's and I'll give you one back.

+rep Nice Guy
+rep Nice Aim
+rep Pretty good for a Silver.
+rep Thanks for the rank-up.
+rep Sweet!
+rep Not bad!
+rep Has got skillz.
+rep Funny Guy.
+rep Even though you raped me in head.
+rep Good at the game.
+rep Ace!
+rep Thanks for the assist.
+rep Thanks for the game!
+rep Was a nice game.

or just leave me a simple +rep.