I HATE SPYS! It's funny when I'm wrecking the other teams snipers and they all get pissed off and go spy and I all of a sudden have 5 invisible people trying to stab me in the back.
Running around with a track athlete wielding a little leaguers bat whacking people (whether killing them or not) is nothing but amusing. Can't get better than that
Changing into an enemy at the beginning of the round, cloaking and running back into their spawn wait for them to come out and uncloak. Stab in the back... rinse and repeat.