MONGOOSE -- (pl. MONGOOSES)
Samuel Goldwyn, needing a pair of this animal but unsure whether the plural was "mongooses" or "mongeese", wrote the following letter: "Please send a mongoose to the studio. As long as you're at it, send another one with it."

LANDSMAN (pl. LANDSLEIT)
Jackie, dear lady, it's so sweet to see you attempting Yiddish! However, I believe the plural of landsman is "landskeit". (I think there's more on this, but unfortunately my Joy of Yiddish was the first book our new puppy devoured.)