I have seen some very interesting handles on PPrune. There are funny ones, traditional ones, serious (by exact name) ones and so on and so forth.
One that has me transfixed though is "---" who is a regular visitor to this forum.
Talking about clandestine!!!! I've done some searching on the site and found a "Morse Code", thus all I can come up with is that "---" must be the absolute top secret clandestine version of Morse.
It's already in Code.