A nervous wreck.
Disclaimer: I don't know how well this joke will work in English. What's yellow and lies in a pond? An excevator. You don't think this is funny? Neither does the operator.
Because they lay out in the sun so much
Wavy!
They use boo-eys.
You've had whey too much!
Shake it off
A nervous wreck! I first heard this at xmas 1952 (64 years ago) and it still makes me smile.