A Snitchnip was a Quidditch foul that occurred when any player (other than the Seeker) caught or touched the Golden Snitch. The team committing the Snitchnip forfeited the game. This foul occurred, along with the other 699 fouls, in the 1473 Quidditch World Cup. It also occurred in the 2014 Quidditch World Cup.
The word Snitchnip is made up of the word snitch and the word nip, which means to brush past or touch. Thus, a Snitchnip occurred when someone touches the snitch.