To give it to a girl from behind.
She got some mean beat cheeks from me last night.
The act of sexual congress.
Yo, them two just beat cheeks about 10 minutes ago.
To have sex
inserting your penis into a vagina (or other warm hole)
Vince: Hey Mark!
Mark: what up?
Vince: Hey I seen you leave with that hottie last night what happen?
Mark: I took her back to the pad and Beat Cheeks!
Vince: NO WAY!, I need to beat some cheeks
Mark: I will hook you up!
To leave the area quickly. Originally from the from the fact that each lobe of your buttock will be slapping together during the act of running.
Cmon man the cops will be here any minute, lets beat cheeks!