If I were a rock, I wouldn't want to be marble because I wouldn't want people to take me for granite.
I told one of my good friends that I was allergic to milk and he said, "No whey!"
I would estimate that I make at least two puns per week. Something someone says will just strike me at an odd angle and the pun percolates out effortlessly. The other day I thought of the above two. I'm not sure if the first is original, but we were in an elevator debating whether the stone walls were made of marble or granite and I couldn't resist. Later that day, someone mentioned cottage cheese and I thought of the second. It's a certified groaner, five out of six friends agree!