You can tune a guitar but you can't "tuna"fish!
Oranges have thick skin. Let the downvotes fly, people! You've only got one! Edit: Did not expect this joke to get this good of a reception. Thanks, guys!
A Dollar
Formed a coustic d'tat
A: A-cue-stick.
Because they can't have land sections
Because pepper makes them sneeze
He kept trying to tune her G string.
You can tune a piano, but you can't piano a tuna.