Blonde in a Double Decker Bus

A blonde, a red head and a brunette board a double-decker bus. There are two seats left on the bottom of the bus and only one seat in the top of the bus available when they board.They decided to take turns riding in the top and flipped a coin to see who got the first turn. The blonde won the toss.A couple of hours later it's the red head's turn so she walks up the stairs, and sees the blonde sitting there scared half to death. She's clutching the seat in front of her so hard that her knuckles are white."What's wrong?" the red head asks. "We're havin' a grand old time down below."The blonde replies, "Yeah, but you've got a driver."