Here's my latest in tongue-twisters - seen on the back of a tee-shirt:
If a fudpucker could puck fud, how much fud could a fudpucker puck if a fudpucker could puck fud.
Say it quickly. How did you do? I had to say it several times before I got it right.
Maybe this is an oldie, and everyone else has seen it. In that case, sorry. Sometimes I don't keep up.