For a time during college I worked at a valet company parking cars at various restaurants and events. At one restaurant we had a regular who came in at least once a week. We used to call him Flip (I don't remember his actual name). Flip was a jovial fellow and would often make small talk with us. Every time on leaving after we had brought up his car Flip would pull out a $10 bill and say, "What's it going to be today guys? 10$ or do you want to flip for it." We always went for the flip. He would pull out a quarter and flip it. Heads doubled your money while tails left you with nothing. Sometimes if you got tails and were disappointed enough he let you flip it again. A fun way to to show appreciation for our work and it made him famous among the valets.