Three Men

Three men were sitting at the edge of the roof on a twenty story
bulding. The first man says "See that path down there. It has a new
safety feature, it's made of highly bouncy rubber. Just in case someone
falls off the roof".
Second man is amazed "Wow, really".
First man "Yeah, watch I'll show you".
With this he jumps of the building bounces on the path and lands back up
on the roof. The second man decides to try this for himself and jumps of
the roof, falls 20 floors and SPLAT!!.
The third man turns to the first man and says "You know you can be a
real bastard sometimes Superman".