I have to agree with some of the others on here. The funniest scene in the entire trilogy, for me anyways, is the Signor Roberto/young Vito scene at Genco Olive Oil, where Roberto comes to apologize. I laugh every single time I see that scene.

"Growing up my dad was like 'You have a great last name, Galifianakis. Galifianakis...begins with a gal...and ends with a kiss...' I'm like that's great dad, can we get it changed to 'Galifianafuck' please?" -- Zach Galifianakis