loophole

Hmm, I thought about this during Christmas. At my walmart, if you buy a game and have it opened, you can no longer return it for a full money refund, but only for an exact copy of the game. So I was thinking... What if I bought a game, played it and beat it, and went to get my money...

well, im ssj trunks and a goku blasts a kamehameha at me. well, naturally i block and try to get into a block struggle. alas, it blew up anyway! i asked the player how, and he said he was 'beam jumpin'! is this suppose to be in the game? if anyone can void out a block struggle than all is lost...