I found this website that lists the "best words." I don't know if they're really the best or not, but apparently you can submit your favorite word(s) to be added to the list. Here are a few of my favorites from their current list. Some I like for the definition, some just for the way the word sounds:
avuncular (ah-VUNG-kyah-ler) — 1. of or having to do with an uncle. (I've heard this word before and really had no idea it's meaning was uncle.)
boeotian (be-OH-shen) — stupid; dull (I think I'd rather just say stupid.)
borborygmus (bor-bah-RIG-mes) — a rumbling noise produced by the movement of gas through the intestines (Here's a whole new way to say you've got gas...)
callipygian (kal-ah-PIJ-ee-en) — having beautifully proportioned buttocks (I don't know why but this one is hilarious.)
clatterfart (KLAT-er-fart) — a chatterer; babbler (Uh-oh...I talk a lot...)
cockalorum (kok-ah-LOR-em) — 1. a little man with an unduly high opinion of himself. 2. boastful talk; braggadocio (I like the first definition; isn't that like short-man-syndrome?)
Okay there's A - C. Perhaps there will be more to come later.