I have. Twice. The first was because of a Control match on Blind Watch. My team started at C, we took B, and proceeded to hold both points pretty easily. Around the time we were halfway to the win, the 1 random guy attached to our 5-man team decided to start pressing for A, and capped it. The entire match went to shit from there. We recovered B and C two or three times, and each time the random douche would cap A again and throw enemy spawns all over. We ended up losing after holding the lead for about 80% of the game time. I think all 5 of us sent a message calling that guy an asshole. I regret nothing. The second time I sent a hate mail was because a douchenozzle kept messing up my Titan bubble trap. He'd snake kills and push me out of the bubble, generally ass-hattery.