Here are some one-liners I read recently that just made me smile.

• For people who like peace and quiet: a phoneless cord.
• Proofread carefully to see if you any words out.
• If I want your opinion, I'll ask you to fill out the necessary forms.
• Look out for #1. Don't step in #2 either.
• A conclusion is simply the place where you got tired of thinking.
• I used up all my sick days, so I'm calling in dead.
• Diplomacy is the art of saying 'Nice doggie!'... till you can find a
  rock.
  
• Shin: A device for finding furniture in the dark.

My favorite:

• If at first you DO succeed, try not to look astonished!