With the exception of Tommy De Vito in Goodfellas, Paulie Walnuts is the most hilarious character ever to appear in a mob movie or series. Furio is far less interesting and does not seem insane.
My favorite moment is the Pine Barrens episode, when Tony calls him on the phone and tells him that the Russian they are after has killed 16 Chechen rebels, was a green beret and has been with the Ministry of Interior. After he hangs up, Paulie tells Christopher "The guy has killed 16 Czechoslovakians. He is an interior decorator."

And Christopher replies "His house looked like shit."