When you and a white male friend have sex with the same girl at the same time. As you are fucking her and she is giving him head, you reach across her and give him a high five signaling that it's his turn to fuck her. It's like when a wrestler tags his partner into the ring during a tag-team match.

Adj. Something that is expected to have a long lifespan by virtue of having existed for a long time, based on the lindy effect, named for the New York restaurant Lindy's, coined by Albert Goldman and popularized by Nassim Taleb.