<human>: Here is a goal: How can I keep my bartender from getting rid of my drink if I have to go to the bathroom quickly?

Which way makes more sense to accomplish this goal?

OPTIONS:
- Place a coaster on top of your drink, this is universal sign for "I'll be back".
- Place a coaster under your drink, this is universal sign for "I'll be back".
<bot>: Place a coaster on top of your drink, this is universal sign for "I'll be back".