The act of using a key to snort a drug. The drug is spooned onto the key and the placed near the nostril for inhalation.
"Hey, Lohan is inviting us to go do a key bump with her in the john."
What you get when your homies are stingy with the bag.
Hitter: "Yo, lay me out a phatty."
Pitcher: "Nah man, I'm just doing key bumps."