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2. RSO
Range Safety Officer

Someone certified by the NRA as a Range Safety possess the knowledge, skills, and attitude essential to organizing, conducting, and supervising safe shooting activities and range operations.
Guy 1: Yo bro who is that guy that just yelled at us?
Guy 2 : That was the RSO, hes a pain.
1. RSO
short term for:
registered sex offender
Dude if you were to do that you'd be RSO
3. RSO
Random Song Outburst
They have lots of RSO's in West Side Story.
"Lalalallalalaaaa" = RSO
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