| JAFFA | Just Another Fat, F***ing Assh*le | - | NASA |
| JAR | JAR Syndrome: Just Ain't Right (often Used When A Patient Has Multiple Issues) | - | NASA |
| JDFR | Just Doesn't Feel Right - Most Common Complaint Of LOL's (Little Old Ladies) And SOG's (Sick Old Guys) | - | NASA |
| JDLR | Just Doesn't Look Right (something Is Wrong, But No Diagnosis Has Been Made Yet) | - | NASA |
| JIC | Jesus Is Calling | - | NASA |
| JLD | Just Like Dad (often Used To Explain An FLK) | - | NASA |
| JNR | Just Not Right (something Is Wrong, But No Diagnosis Has Been Made Yet) | - | NASA |
| JPFROG | Just Plain F***ing Ran Out Of Gas (old Age, Etc) | - | NASA |
| JPS | Just Plain Stupid (self Induced Injury Involving Lack Of Common Sense) | - | NASA |
