Why are guys "addicted" to COD & Black OPS?

I went to my friends pool party yesterday (which was awesome) but before we went into the pool everyone went upstairs in the living room and I saw the guys (from my class) playing COD and they are screaming at the TV like if its so realistic ! Like my guy friend was screaming WTF you killed me and his friend .. They weren't even killing anyone.. They were shooting the stupid wall !! Like gosh if the game wasib 3D they would act like hooligans !!! Lmfaooooooooo