Effective command of Chilango slang will allow you to react promptly to precise driving indications in Mexico City. One of them is en uñas (en OO•gnass), which literally means "in finger nails." En uñas is used in the expression darse la vuelta en uñas, which means to make a U-turn.
Darse la vuelta en uñas shall not be confused with ser uña, which literally means "to be a finger nail." Ser uña means to be a slimy stealing rat with long nails serving that purpose, i.e. to be a thief, un amigo de lo ajeno, a friend of someone else's belongings.
Another pertinent distinction should be made with the expression en 20 uñas (on twenty finger nails) which conveys a body position in which one partner in sexual intercourse has twenty nails on the ground.
Joselo: Echale lámina a la micro y date vuelta en uñas ahí donde está la señal que lo prohibe.
Joselo: Let the bus know your switching lanes and make a U-turn where the 'no U-turn' sign is.
Quique: All right.