Note: To all, not enough jokes have came in so I will extend the contest for another week and if nobody enters I will end it. Sorry.
Here! I'll post one!
OK, so there's three Minifigs going for a walk in the desert on a hot summer's day. The first Minifig brings a bottle of water and says, "If I get too hot I can drink water to cool me down." the second brings a fan to keep himself cool, and the third brings a car door. The others ask why, and without hesitation, the third minifig says "Well... if it gets to hot then I'll wind down the window"!

Not great, however it's my best attempt on a classic joke. 0:)