When one person purposely bumps another persons booty with their own booty.

it means putting some pep in your step.

Snorting a line off a hot bitch's ass.

When two lesbians come together one attaches a strap on to there butt and the other spreads their ass cheeks as far as they can and they bump them together

Booty bump is when you take a shard and shove it up your butthole. Then have someone stick their penis in your butt and start bumping