A lawyer and his friend are in a bank when armed robbers burst in. The customers, including the lawyer and his friend, are thrown up against a wall, and the robbers proceed to grab their wallets, watches, etc.

While this is going on, the lawyer jams subtly slides something into his friend's hand.

Without looking down, the friend whispers, "What's this?"

The lawyer replies, "It's that $50 I owe you."