literally, "kill it!" It is usually an interjection. It comes from the Spanish verb, "matar", which means, "to kill." the lo is a direct object pronoun used for masculine objects. The pronoun "la" is used for feminine direct objects. You can also say "matale" which means not only kill him, but also her. Gender doesn't matter in that instance.
Un serpente, papi matalo
by Martirio Graciela Ayala July 21, 2007