Gañán (gah • GNAN) is used in reference to a male person whose behavior is tasteless, rude or inappropriate. In short, a gañán is a prick. It's usually heard in the context of a guy trying to catch the attention of a female with low-down or insulting techniques.
Agustiniano: ¿Qué pasó con Margarita?
Filiberto: Me dejó de hablar porque le dije que me encantaría 'gratinarle su mollete'.
Agustiniano: ¡Eres un pinche gañán!
Augustiniano: What happened with Margarita?
Filiberto: She stopped talking to me cause I told her I'd love to 'melt my cheese on her bean-covered toast'.
Agustiniano: You're a fucking prick!
Molletes are a delicious breakfast dish in D.F., that consists of demi-baguettes cut in halves, covered with refried bean spread, and topped with cheese and salsa.