I think Pete could manage a light ghosting of his fingers over the swell of Patrick's ass. The way he's sitting and leaning forward just makes think Pete had fair access to the slightly lowered back of Patrick's pants.

EITHER WAY THAT'S WHAT I SEE IN MY HEAD. Because Pete is all "come on" and lets his fingers drop and Patrick tries not to let his eyes slide shut and says "oh, gross" to remind Pete that this isn't the time for such things. :D