Make a sign that says, "Hot Oral Sex".
On a related note, people are very trusting. First dates nowadays and you might end up with your genitals in someone's mouth. Putting sexual organs in a potentially dangerous setting (bacteria, virus, teeth connected to a mandible with malicious intent) deserves more research than that which is don for where said dinner prior to happening may occur.
It's the same as walking up to someone in a subway and asking them, "We have just met and this may sound crazy, but I can put my cock and balls in your mouth."