Da Ali G Show hasn't aged as well as such classics as "Football Hits Groin" and cakefarts, but god this stuff takes me back. How he keeps a straight face I'll never know.
Hilarious bit.
I don't consider this underrated, but this is a great bit.
From the late great Robert Schimmel:
Robert George "Bob" Schimmel (January 16, 1950 – September 3, 2010) was an American comedian who was known for his controversial blue comedy.[1] While the extremely profane nature of his act limited his commercial appeal, he had a reputation as a "comic's comic" due to his relentless touring, comedy albums and frequent appearances on HBO and The Howard Stern Show. Schimmel is number 76 on the 2004 program Comedy Central Presents: 100 Greatest Stand-Ups Of All Time.