A very quiet man who works at an industrial plant walks out the front gate every night with a wheelbarrow full of sawdust.  As the nights go on the sawdust is piled into higher and higher piles ontop of the wheelbarow, and the gate security operator naturally becomes suspicious.

He asks him, "What have you got that wheelbarrow there, sir?"
"Nothin'.  Sawdust."

The operator finally begins to search through the piles night after night, but to no avail.  He even brings out the plant security to check him, but nothing is found.

One night, the gaurd has had enough, and says, "Alright, Fred, enough is enough!  What the hell are you takin' out of this damn plant!?"
"Wheelbarrows."

LOL!