When one pulls out of ass, only to discover a nugget of shit on the end of ones cock. Then one picks it off and throws it at the unsuspecting victim while screaming "SCOOBY SNACK!"
Dan pulled out of Emma last night only to discover a Scooby Snack!
A variation of the rusty trombone in which the man receiving the rusty trombone takes a dump in the mouth of his partner as they are licking his anal hole.