They ask the hotel manager "How much for one room?"
Manager says "$30. That's $10 bucks for each guy." 10+10+10=30
They go up to the room.
Manager says "I made a mistake! The room is $25, not $30!"
Manager gives the bell hop $5 and says
"Take this five bucks up to the 3 guys."
Off goes the bell hop with the $5.
But the bell hop guy is a little dishonest, and scoffs,
"Hmph! $5 divided by 3 guys? No freakin' way!"
The bell hop takes $2 and gives each guy back $1 each. 1+1+1+2=5
He says "Hey, guys, uh, the room is $9 a night, not $10 each.
So here's a dollar back for each of youse."
So now each guy has paid $9 each 9+9+9=27
And the bell hop kept $2 27+2=29
Where is the other dollar?
They started out with $30
This is why I don't weigh.