Needing a girl (bit naughty)

An old gentleman slowly approached the local brothel and pressed the doorbell.

The madam opened the door, looked at the old fellow with a critical eye and then asked. "What can we do for you, sir?"

"I need a girl" the senior citizen said.

"For you, the charge is a hundred dollars".

"You're putting me on!" he exclaimed.

Spoiler:

"That will be an extra ten dollars" said the madam.