here's an old one
Q: a helicopter is flying with 500 bricks. a man in it throws one brick out. how many bricks does the helicopter have now?
A: 499
Q: how do you put an elephant in a refrigerator in 3 steps?
A: open the door, put the elephant in and close it.
Q: how do you put a giraffe in a refrigerator in 4 steps?
A: open the door, take the elephant out, put the giraffe in and close the door.
Q: all the animals in the world gather for a special meeting headed by the lion. but one animal is missing. who is that?
A: the giraffe, cos he's still in the refrigerator.
Q: an old lady wants to cross a river which has water only knee deep, but inhabited by man eating ferocious crocodiles. the river has no bridges or boats. how does she cross it?
A: she simply walks through it, as the crocodiles have gone to the meeting.
Q: the old lady walks through the river but falls dead half way across. why?
A: cos she got hit on the head by the brick thrown off the helicopter!