| Abbreviation | Definition |
|---|---|
| IROC | Idiot Right Out of College |
| IROC | Idiots Rely On Chevrolets |
| IROC | Ignorant Retard Out Cruising |
| IROC | I'm Really On Crack |
| IROC | I'm Really Only a Camaro |
| IROC | Italian Resting On Console |
| IROC | Italian Retards Out Cruising |
| IROC | Italian Roney Out Cruisin |
| IROC | It's Really Only Chevrolet |
| IRS | Improving The Republican Summer |
| IRS | Income Revenue Service |
| IRS | Infernal Revenue Service |
| IRS | International Riot Society |
| IRS | Invisible RattleSnakes |
| IRS | Irate Raging Spouse |
| IRS | It's Really Stealing |
| IRV | In room vending |
| IS | Idiots for Socialism |
| ISAIKI | I'm Sexy and I Know It |
| ISB | Irish Stud Book |