To check someone's buttocks for something concealed there, often drugs. If the police are suspicious, they're going to give you a booty check.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
n. a search of the rectum, as when police look for drugs. Willie got arrested and had a booty check since he was walking funny.
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.