Pretty much the same as 'Sucking Up' to someone, except based around the action of giving somebody anal sex.
"I can believe you bum up to him just because he has a nice car."
"Dave's bumming up to Celebrities again."
a way in telling a person to "Come up"..started by bloods and they dont say the letter "c" so they would say "bum up"
get there stuff togetha..get fresh..Fly..ect.
-Get like meh...BUM UP!