| | J.A.L.N. | | Just Another Lonely Night |
| | J.C.T.S.I.L.Y. | | Just called to say I love you |
| | J.F.C.O.M. | | Joint Forces Command |
| | J.T.A.Y. | | Just thinking about you |
| | J2EE | | Java 2 Enterprise Edition |
| | JATD | | Just a typical day |
| | JAWS | | Just Another Windows Shell |
| | JBOD | | Just a Bunch of Disks |
| | jbyam | | Just between you and me |
| | JC | | Jesus Christ |
| | JC | | Just Curious |
| | jcath | | Just chilling at the house |
| | JCP | | Java Community Process |
| | JD | | Jack Daniels |
| | JD | | job done |
| | JDBC | | Java Database Connectivity |
| | JDI | | just do it |
| | jdo | | java data objects |
| | JDOM | | Java Document Object Model |
| | JDS | | Jack Daniels |
| | JDS | | Java Desktop System |
| | JDTR | | Just Down the Road |
| | JES | | Java Enterprise System |
| | JFCOM | | Joint Forces Command |
| | JFI | | Just For Information |
| | JFI | | just forget it |
| | JFMAMJJASOND | | January to December |
| | jj | | Just Joking |
| | jlu | | Jesus loves you |
| | jlyk | | just letting you know |
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