| Abbreviation | Definition |
|---|---|
| OSAMA | Oh S*** American Missiles Again |
| OSAMA | Oh S***! American Missiles Again! |
| OSCARS | Orange Shiny Cucurbitas Are Really Spectacular |
| OSCE | Organisation for Seriousely Confused Europeans |
| OSCE | Organization To Secure Clinton's Election |
| OSHA | Occasional Safe and Health Association |
| OSHA | Occasional Safety and Health Advice |
| OSHA | Oh S*** Happens Anyway |
| OSHA | Oh Shit Happens Anyway |
| OSHA | One Should Have Accidents |
| OSHA | Organization of Supposedly Helpful Acts |
| OSHPOT | On Slim Hateful Pants Over Toolbox |
| OSP | Overly Sloppy Person |
| OSU | Oklahoma Scares Us |
| OSU | Old Stinky Underwear |
| OSU | Old-style Soviet University |
| OSU | Optimists Submit Urine |
| OSU | Orangatang Socializing University |
| OSU | Oregon Second-rate University |
| OSU | Oregon Snowflake University |