When you want to leave something because you don't like it, in Argentina, people says "a la mierda" as his equal in english for "fuck it".
A variant is "andate a la mierda". Instead of talking about something as in "a la mierda" it talks about someone. His equal in english is "fuck off".
Joey: Man, we have to do the Spanish class homework.
Matt: A la mierda, I don't wanna do it.