My favorite was at a party where the (verbal) quiz question was what a "yamikah" is. I had absolutely no idea. Then they told me what it was, and I said - as if the quiz question had gotten it wrong - "Ohhhhh! You mean a YAR-MULK."
Something similar happened to me: a friend of mine kept telling me he worked for a security company called Semantic, and much later I realized he meant Symantec (pronounced like "semantic").
