It is when someone tells you something and you don't believe it whilst it will never happen. Mostly used when people lie all the time.
guy1:hey dude i fucked a girl
guy2:no way man
10mins later
guy1:dude man i really fucked a girl
guy2:srsly dude thats multi-bull
guy1:oh yeah how?
guy2:your fat and ugly
guy1:well
guy2:and remeber that time when u said that a girl gave you a bj, that was also multi-bull cuz ur penis is so short xD
guy1:oh stfu
guy2:no way man
10mins later
guy1:dude man i really fucked a girl
guy2:srsly dude thats multi-bull
guy1:oh yeah how?
guy2:your fat and ugly
guy1:well
guy2:and remeber that time when u said that a girl gave you a bj, that was also multi-bull cuz ur penis is so short xD
guy1:oh stfu
by [x]Media400 May 21, 2009