Fusilar (foo-see-LAHR) literally means to execute by firing squad. However, in Chilango slang it means to copy usually without any permission. The result of such copying is referred to as fusil (foo-SEAL), which literally means rifle.
Maestra: ¡Muy bien, Pepito!
Pepito: No se haga, maestra, luego-luego se ve que es fusil.
Maestra: Pues sí, pero normalmente te fusilas las tareas equivocadas.
Teacher: Very good, Pepito!
Pepito: Drop it, teacher, you can immediately tell I cheated.
Teacher: Yup, but you normally cheat by copying the wrong assigment.