It means Rolling On The Floor Laughing My A** Off

>>The TSA doesn't have time to look at the text..don't worry.

Depends on who's doing the search and how dishonest, incompetent and/or unhurried they are.

Last December TSA-PHX got into my TSA-locked duffle, ripped open a sealed but unaddressed Priority Mail envelope, left its contents scattered throughout the bag damaged (among other things). Dot was red (indicating TSA-key use) and they left the love note. This envelope was a millimeter or less thick, contained nothing but paper: no way did it alarm the XRM.

I use indicator TSA locks and unusual-coloured zip ties both, depending on what I must check that trip and which luggage I'm using. Sometimes they do a neat search and replace the zip ties with white or black ones, other times they leave exterior pockets unzipped, compression straps loose or gone, etc.

To OP: nothing's dependable. Use what you like, and hope for the best. If you can manage with only carry-on, better still. Gute Reise!