Here's a great collection of puns and oneliners. For the full list, check out bits and pieces.
2. A will is a dead giveaway.
6. When a clock is hungry it goes back four seconds.
10. A calendar’s days are numbered.
14. Those who get too big for their britches will be exposed in the end.
19. Acupuncture: a jab well done.
25. No matter how much you push the envelope, it’ll still be stationery.
30. I wondered why the baseball kept getting bigger. Then it hit me.