If I were a mischevious tailor, with a customer I didnt like
I'd put just enough of this thread (concealed in the lining of a jacket of course) to show the outline of, say, a handgun under the armpit. It would take the TSA ages to work it out as they tried searching for what the scanner showed them was there.
Now if I owned a clothing factory, somewhere like China, I could introduce this surreptiously into mass produced clothing for a totally random effect. Travel chaos!
Random other shapes could also be used, dynamite sticks, daggers etc
Myself, I'd try one with a big comedy "bomb" on my vest, filled in with the word as a cutout.
Actually my boss is off travelling shortly. Can you get something that shows up on the scanner as a spray? I've some stencils somewhere.....