I used to work in a seafood restaurant, and there was a counter for selling fresh fish. A lady came in and asked to buy some "swimps". Very seriously I asked "what size shrimp?" She said "beeg swimps!" And I swear I didn't mean to, but out of my mouth came "O! You mean pwawns!" The guy next to me was no help he just sank beneath the counter in fit of silent laughter. She gave me a look of such venom I stepped back the apologetic expression on my face very real, but before I could say anything else she stormed out. Go ahead - say it out loud - "pwawns"