The act of removing a ceiling tile from the bathroom ceiling, shitting on it, and putting it back. Eventually the smell becomes unbearable, but no one knows where it is coming from.
When you unscrew someone's showerhead and fill the inside with feces. That way the next time they take a shower they will literally be covered in shit. Similar to the Upper Decker, the SkyBox is a step above.
A-"That asshole forgot to lock his door so I left him a present."
B-"What'd you do, give him an Upper Decker?"
A-"Nah, this dick deserved more, so I SkyBoxed him."
B-"You sick bastard!"
One better than the upper deck. Instead of taking a shit in the upper tank, you take a shit on top of the upper tank. Where the upper deck is a delayed sabotage, the skybox is a blatant act of defiance.
I can't wait to see the look on Marty's face when he finds out I skyboxed his toilet!