Fellas, if their butthole looks like a hypnotic vortex; that ain't a butthole, it's a portal to an extra dimensional Freudian TV show.
The depth buffer is a parameter used to help determine which objects are covering up other objects so that only what should be visible is rendered. Crazy visual artifacts (or glitches) can occur when this isn't configured properly.
Fellas, if their butthole looks like a hypnotic vortex; that ain't a butthole, it's a portal to an extra dimensional Freudian TV show.