Anyways, this fic is one set after season 2 and the ketamine treatment. During the summer inbetween, if I'm not mistaken. House is on a run and ends up at Cuddy's house. When she answers the door he says something like 'I can't breathe' and she invites him in. He has his shirt off, and while drinking water Cuddy admires the way some of it runs down his chest, etc etc. Then I think he goes and takes a shower, then smut ensues when he gets out.
EDIT: it's Queenzulu's Lazy (III)