"A Man's Best Friend" joke

A man phoned up an exclusive escort agency and asked for a woman.
"No problem," said the receptionist.
"There's just one thing," said the man,"she has to be 6' 6" tall and weigh 48lbs."
"Mmm, let me see -yes we can do that for you, but it will be expensive," said the receptionist.
"That's o.k," said the man.
"When do you want her?".
"Tomorrow night at 7pm," said the man.
The next night the doorbell rings and a painfully thin 6' 6" black woman is standing on his doorstep.
"Come in, take off all your clothes and go down on all fours," said the man.
She complies with his request.
He opens the kitchen door and a scrawny black labrador emerges.
The woman thinks, "Oh shit, what have I let myself in for?"
The man points at his dog and says, "Now that's what you'll look like if you don't eat all your dog food."