What is Spycheck?
1.
A method of behaviour in the multiplayer game Team Fortress 2. Spycheckers will randomly attack all friendly players in the hopes of finding a spy. They spend a good deal of effort for a few amount of points, and such behaviour is probably motivated by past traumatising experience of being backstabbed by enemy spies.
"I hate spies so much, i'm gonna spend my entire hour Spychecking!"
See
2.
In the popular multiplayer shooter Team fortress 2 made by VALVe, you can choose a class named spy, and that spy can turn himself invisible. So it is impossible to spot him and so there is a pyro class which can set invisible spy on fire and make him visible for other clases
Engineer:"Ah man, it's a Spy 'round here!"
Pyro:"SPYCHECK!! SPYCHECK!!" (turning around while holding trigger of flamethrower)
See