Prrrum
The sound that a Glock pistol (modified to be fully automatic with a 30 round magazine) makes when discharged. This type of weapon is popular amongst Puerto Rican gang members for administering street justice in the caserio quickly without all the pretentiousness and awkward size associated with full sized assault rifles. This modified pistol's unique sound (caused by it's small caliber and rapid rate of fire) is verbally mimicked as "Prrrum" in circles that are familiar with the weapon. (This was explained by a Borriqua from Santurce, P.R. around the time when Coscullela's song, "Prrrum" was released.)
I'm gonna kidnap this guy's hot girlfriend from a disco, and if he has a problem with it, he can ask for "it" in the disco or on the street, and my fully automatic Glock pistol with a 30 round clip will say "prrrum, prrrum, prrrum". (This usage example is a rough translation of Coscullela's song, "Prrrum", that popularized the use of the word.)
Prrrum
Word made famous by Lele "el arma secreta" and then wrote a song for Cosculluela with the same title.
"prrrum" - Cosculluela