这集TBBT好看到爆啊

bazinga is being used as a shout of joy as in 'ha' or 'gotcha' and would be used when you complete a level or more in a game, similer to 'house' in bingo when you win or 'howzat' when you get some one out in cricket you know that sort of thing. and as i would imagine the character of sheldon dos'nt play actual sports a computer game would be the nearest equivilant.