Used as a coarse intensifier appended to a noun or adjective to express strong contempt, derision, or emphasis (e.g., as an insult meaning 'complete fool' or 'utterly useless').
2.
SpainLatin Americavulgarcolloquial
Used to indicate poor quality, incompetence, or that something was done very badly (equivalent to 'messed up' or 'done terribly').
3.
SpainLatin Americavulgarinformal
Occasionally used in locutions to convey crudeness or baseness of subject matter; broadly denotes something contemptible or contemptuously low.
Examples:
ES: El campeonato mundial de los tontos del culo.
EN: World champion of saps.
ES: Después de la mula, Dios creó el culo, y después del culo, el legionario.
EN: After the mule, God created the ass, and after the ass, the legionnaire.
ES: el Renacimiento... y ahora la civilización del culo.
EN: First there was Greek civilization. Then there was the Renaissance. Now we're entering the Age of the Ass.
ES: En buen inglés, tonto del culo.
EN: That's old English for, deaf and dumb.
ES: - Te voy a machacar el agujero del culo!
EN: I'll flatten you, you asshole!
ES: - Les has quemado los pelos del culo.
EN: That burnt the hairs off their ass.
ES: - Los pelos del culo...
EN: -Hairs off their ass...
ES: Es el lomo y parte del culo del conejo, señora.
EN: It's the back and rear of the rabbit.
ES: Un tonto del culo, mamá ¿Un qué?
EN: A faggot, maman. A what?
ES: Pierrot nos manda un tonto del culo.
EN: Pierrot has sent us a faggot.
ES: Lo sabrás cuando pasen, ¿no crees, tonto del culo?
EN: Can't know until they come, can you, dumbass?
ES: Lárgate, tonto del culo.
EN: Get out, you great steaming nit.
ES: Se agarró del culo, corrió al abrevadero y se sentó allí.
EN: He grabbed his bottom, ran for the watering trough, sat down in it.
ES: Está bien, si vino del culo a la cabeza.
EN: It's fine, if it came from the ass to the head.
ES: ¡Eh, tú! Duquesa del culo, si quieres conservar a tu hombre has de usar tu influencia para que sepa cuáles son tus gustos.
EN: Hey, Duchess, if you want to keep your man alive, you better use your influence to let him know what's good for him.
ES: He llegado a ver una vaca que llevaba un ternero muerto colgandole del culo, estaba pudriendose.
EN: I saw one cow with a dead calf hanging from its rear, already rotting.
ES: ¡Tonto del culo!
EN: You idiot.
ES: La cultura del entretenimiento. La cultura del llavero. Y la cultura del culo.
EN: The culture of leisure, the culture of the key chain, and the culture of sex.