it means shut the *$#@ Up! or it can also mean your done talking or that your talking privileges have been revoked for the remainder of the day.
Some one is saying something stupid or they are about to say something they shouldn't so you cut them off and say "bup-bup"
Por toxictrix 15 de octubre de 2009
the dried tomato on the top of the ketchup bottle.
oh no, this ketchup bottle has bup-bup on the top of it, someone scrape it off!
Por sydney brair smith 18 de febrero de 2008