Here's one that everybody knows...
So a guy walks into a bar and sits down. Then he reaches into his pocket and takes out a small lantern. He rubs the lantern and then again he reaches into his pocket, feels around a bit and takes out a miniature piano. Seemingly puzzled he reaches into his pocket once more and out comes a man who is twelve inches in height! He sits down at the piano and starts playing, he plays Bach, Beethoven, Chopin, Schumann, and to top it all off he plays a little boogie woogie.
The bartender watching this is amazed and asks the guy about the incredible sight he has just witnessed.
The guy says " See this here lantern, it's a magic lantern. If you rub it and wish for something, it'll come true!"
Now the bartender wanting to try this out for himself snatches the lantern out of the guy's hand and starts rubbing it. All of a sudden, the bar is full of ducks. Ducks are every where, quacking on the bar table, flapping their wings on top of the pool table pecking on the beer taps and so on.
The bartender getting angry says " Hey, what happened, I asked for a million bucks!!!"
The guy replies " Don't get angry with me, you think I asked for a twelve inche pianist!!??"

Actually that was a new one on me.I liked it.

Here's an oldie but a real favorite of mine.

 One day Superman decides to take a day off.He's tired of always helping everyone and needs a day to himself.So he puts on his cape and takes off.

 Soon he flies over Batmans's house.Batman is waxing the Batmobile.Superman thinks to himself...

"Ya know..I'd love to go down there and say hello to the guy but I know what'll happen.He'll put me right to work with my super speed and I'll wind up waxing that Batmobile.Well,I'm not working today...I'm taking the day off!"

So he keeps flying.He then flies over Captain America's house.Cap is loading shingles onto his roof.Superman thinks...

"I'd really love to fly down there and bullshit with the guy but as soon as I do,he'll put me to work with my super strength loading that roof.Not happening."

He continues on his way.Eventually he flies over Wonder Woman's house.Now Wonder Woman is lying by the pool wearing nothing but a smile.Her legs are open a little bit and she has a sexy look on her face.Supe thinks...

"Oh man!I know...I'll fly down there with my super speed...WHAM!...I'll let her have it...ZOOM!!...I'll fly off...she'll never know what hit her!!"

And so he does...WOOSH!!!He flies down...has his way with her...and ZOOOM!!...he's gone in a flash!

Wonder Woman says,"Holy crap!!!What was that???"

And the Invisible Man replies,"I dont know,but it got me right in the ass!!"