Biggie - This is unusual. A biggie is what a child calls his poo! Hence the reason Wendy's Hamburgers has never really taken off in England - who would buy "biggie fries"? Yuck - I'm sure you wouldn't buy poo fries! The other meaning of Biggie is erection. It just gets worse!
Rest here:
http://www.effingpot.com/slang.shtml