All you need is a match, two pint glasses and a quarter, and you'll be drinking free all night!
We've said it before, and we'll say it again: the tricks win you goodwill, but the puzzles win you good beer!
The Setup: turn an empty pint glass upside down, and place a "treasure" inside (in this case, a $5 bill). Set another empty pint glass upside down next to it. Finally, set up the "alarm system": a match, suspended between two pints.
The Challenge: Liberate Abe Lincoln from his pint-glass prison, without setting off the "alarm system". You can use anything on the table, but you can't touch the match, you can only touch one glass, and the moment the match loses contact with the pint glass holding the money, you lose. Can you do it?
The Solution: Use another match to light the head of the "alarm system" match. Just after it flares up, blow it out. You'll find the match is now tenuously fused to the pint glass. With a steady hand, you'll be able to lift the pint glass, taking the match along with it. Remove the bill, replace the glass...and order yourself a free beer!