How about when Sonny's wife was describing his "size" to the other wives and bridesmaids at Connie's wedding.

Here's another one that always makes me laugh.

When Paulie is looking at Connie's wedding purse.

"Twenty- Thirty-grand. In small bills, cash. In that little silk purse. Madon', if this was someone else's wedding, sfortunato" - quote taken from the transcript at thegodfathertrilogy.com

Just how he says it, is classic!