I didn't know about these because I don't go into women's restrooms in nightclubs.
Bars lately are coming up with secret codes to help customers signal, privately, when they need help if they're getting harassed or feeling unsafe on a bad date.You learn something every day. More information at the link.
At one Tampa restaurant, that code was the Angel shot. Depending on how the shot was ordered (neat, on the rocks, with lime), the bartender would know the person needs a ride home, a walk to their car, or a secret call to the police. Women receive the intel about the secret-code drink order via a discreet sign in the restroom.