A doctor and a lawyer are chatting at a party. Their conversation is constantly interrupted by guests describing their aches and pains and asking the doctor for free medical advice.

After about an hour, the frustrated doctor turns to the lawyer and asks, “What do you do to stop people from asking you for free legal advice when you’re away from the office?”

The lawyer smiles. “I give them the advice… then I send them a bill.”

The doctor is shocked by the suggestion, but decides to give it a try.

The next day, still feeling a little guilty, the doctor prepares the invoices.

As he opens his front door to head to the post office, he notices an envelope on the welcome mat.

It was a bill from the lawyer.