Hacker.
Guy's got no hit-reg.
Right clicked instead of left clicked. (Happens quite often in my case, annoying on CS when you've got an M4 with a removable silencer)
Game keeps lagging every time I see an enemy. (Not my excuse but other's use it a lot)
He warped out of no-where. (Happens once in a while because the servers I go on are rubbish)
iTunes makes the game lag every time it changes song. (Happens all the time, isn't even an excuse, it's the truth. Should probably use another program to listen to music)
Pressed the Windows key.
Was talking in Steam Chat. (Happens a lot)
My cat just jumped onto my desk. (Happens once in a while)
Went to get my dinner.
Hell froze over. (Happens every day)
Not really funny but that's just some of my assortment of excuses.