I love Fredo!! He is so funny! Great thread idea, btw. Some Fredo funnies:

"How do you say banana daquiri?"
"Mama used to say I was left on the doorstep by gypsies. Sometimes I think it's true."

there are more Fredo funnies but I can't think of them right now....

Also in Part I when Sonny gets that fish and asks what is this - makes me laugh.

Kay makes me laugh in Part I at the beginning because she seems so dingy and ditzy.

Actually a lot of it could be seen as humorous, and I think that's why there have been so many parodies of the Godfather in TV shows, etc....