Spectorbating 

Masturbating while watching two people get in on.

It would have been a manage-a-trois, but I just sat on the sidelines spectorbating.

Spectorbating by Fucking Russ October 11, 2011

spectabating

Masturbating while spectating other activities - including (but not limited to) video-games.

The game-server administration is connected in-game but unavailable, because he is busy spectabating, or
The admin tends to not actually play the game, and instead just spectabate.

spectabating by Mecha-Weasel June 17, 2018