Top Definition
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
by [x]Media400 May 20, 2009

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