Sexomnia clip
The official YouTube channel has lots of clips. This one most popular with 18M views.
https://youtu.be/WR7teEjB_YU (4m)
A woman comes to the clinic showing symptoms of pregnancy but when she tells House that she's not been sexually active in over a year, he discovers a startling reason for her health problems!
Season 1 Episode 17 - Role Model
Second place: Wilson on Speed: https://www.youtube.com/watch?v=ObWzvqknX2A