There was a Mythbusters episode about farts and Adam kept saying “flatus” in this very proper voice and I thought it was hilarious. I try to say “flatus” in that same voice whenever possible.
Papillon is a fun word. Oh, and perspicacity or perspicacious. Those are so much fun Apparently words with a couple of "p"s are fun for me. There are others, but those are the ones that came to me right away.
Kinshasa. I've always loved it. Then I made a friend named Kinshasa and she was like "oh, my name is from .. ." and I was like "The capital of the Congo? Where the Rumble in the Jungle was? I KNOW!" Because it's not that often in my daily life I get to say "Kinshasa."