A derisive word used to belittle and demean another individual, especially if they happen to be spanish/mexican/dirty. Puto has a similar connotation as calling a man a "bitch" but may also be used in reference to any dirty slut who deserves it.
hombre #1: "I ain't afraid of no jail meng"
hombre #2: "You should be. They're gonna pass your puto ass around like currency"