It originated in 2000 around South Gwinnett in
Georgia and it means "Definitely" or "Im excited" or "I can't wait"or "For sure" or "Cool beans" or "Im down" or "Im
game" or "I
will be there" or "Yes" or as an updated version of saying "You bet" or "You betcha" which means you agree and are looking forward to an upcoming event/plans of some sort.
Dude: Are you coming to the club tomorrow night? They
said Usher is performing and there
will be
hella chicks there"
Dude 2: Fuck yeah bet that up!