Two friends, Jim and Paul are in a bank, when, suddenly, armed robbers burst in.
While several of the robbers take the money from the tellers, others line the customers up against a wall and proceed to take their wallets, watches, etc.
While this is going on, Jim slips something into Paul's hand. Without looking down, Paul whispers, "What is this?"
Jim replies, "It's that $50 I owe you."