He was on the third episode of House MD season 1. I think he was briefly shown naked (with a little bit of peen showing). The Wikia page mentioned he is the only character in the entire series to be completely naked.
First post ever...
So, after reading this, two things have happened:
1) I am now watching the entirety of house,
2) He is, indeed, naked in that episode. I've done my best to capture the scene - hopefully someone else can work their magic! I put in a bonus photo as well.
I'm assuming the full files can be opened in another window but, if not, I can upload again or get more caps.