tener morro

Literally "morro" means lips (morros) or snout
"Tener morro" is when some people don't pay and the rest of the group have to pay for them all the time, friends who don't buy new clothes and use yours, smoke everyone's weed but never pay, drink from your glass, eat your food...
Normally you tell them "tienes mucho morro" while softly and repeatedly slapping your cheek (like a girl powdering her face).
Some names for these people are: gorrón, caradura, rata, jeta, morrudo, sinvergüenza...
Some other synonims of "tener morro" are: tener un morro que te lo pisas (to have a snout so big you can step on it), tener más cara que espalda (to have more face than back), tener la cara dura (to have a hard face), tener jeta...
Sometimes "Rata" not only means this but also the opposite: to never share or invite other people, like a rat.

+Oye tío, ¿me das de fumar?
- Si hombre, no te voy a dar más que siempre te lo fumas todo y luego no invitas, tú lo que tienes es mucho morro *slapping himself*

+¡Pero qué morro! Deja de comerte mi comida
-No seas rata, que yo siempre comparto contigo
+Anda calla ya y deja de tener morro