This is when you've been playing loads of games/watching loads of films/TV or looking online for an incredible amount of time and you get the symptoms of a numb butt, stiff achy muscles and pins & needles in various places, a bit like when you're bed ridden in hospital or something for too long.
Ty: Is Dave gonna come with us to see the movie tonight?
Chino: Nah dude, he's got that new game.. won't see him for months!
Ty: Oh man, he's gonna be covered in Sofa Sores!
Chino: Hahah ain't that the truth!
Ty: I'm over it. Let's go.