An initialism for "if it ain't broke, don't fix it," meaning don't fiddle or interfere with something that is functioning just fine as it is. If the washer's working, you should text him IIABDFI so he doesn't bring his tools over and try messing with it.
If it ain’t broke don’t fix it
and IIABDFI
sent. & comp. abb. Leave well enough alone.; Don’t tamper with something that is all right as it is. It’s fine. Leave it alone. If it ain’t broke, don’t fix it!