When you are doing a chick from behind and you quickly pull out letting your buddy emerge into the roomunsuspected and undetected and finishes the job while you exit the room.
When someone does not say anything / tag others in funny memes / show up to friend events for a long period of time. Also doesn't seem to have interest in guys nights.
In Naruto Merdapostagem(an brazilian group of jokes/memes about Naruto), there are a lot of ghosts complaining about the current content. Why don't they try to be active members?