Barrett .50 Cal.
Although only when called for, I love this weapon and I've used it so much than within less than a day I snagged Blue Tiger camo for it, working my way towards Red Tiger.
Aside from that, when I'm not playing sniper, it's either the P90, just because I'm a Stargate fan and it's the weapon that the entire cast tend to use most, or failing that, G3.
But if I'm actually LOOKING to annoy people, which is rarely, AK-47 with n00btube + Sonic Boom + Martyrdom = 12 year old kids yelling down the mic at you. :lol: