A parasitic criminal who wears flashy clothes and greasy hair to attract cholas, and who assaults and batters (or stabs) innocent passers-by. The Pachuco is of Mexican heritage, but rejects it in favor of acting like a punk.
Oh, sweetheart, can we cross the street please?
Yes, darling. Why?
Oh, there's a Pachuco over there and I'd like you to whoop his greasy ass so we won't have to see him when we come back.