| Abbreviation | Definition |
|---|---|
| OAB | One Angry Boy |
| OABC | Observe And Be Curious |
| OAK | One Of A Kind |
| OAN | On Another Note |
| OAO | Over And Out |
| OAO | Over And Over |
| OAP | Old A** Person |
| OAQ | Occasionally Asked Questions |
| OAT | One At a Time |
| OATUS | On A Totally Unrelated Subject |
| OAYOR | Open At Your Own Risk |
| OB | Obnoxious Because |
| OB | Odd Ball |
| OB | Old Buddy |
| OBBY | Obstacle Course |
| OBGD | Ok Bye Good Day |
| OBGYN | Oh Boy Got You Naked |
| OBNW | Our-Brave-New-World |
| OBOE | Overcome By Other Events |
| OBOI | Oh! Boy! |