jacking off in a corner
When a person is too lazy to even pretend they're doing anything important, and just disappears to jack off in a corner like it's their full-time job.
He left the game to go somewhere. We all know he was taking a solo trip.
She said she had to go to the bathroom. We all know she was getting her rocks off.
He vanished mid-sentence. We all know he was taking a break.