In the 1960s and early 1970s just about every overseas station had a dayglo "zapp" that would be found on your aeroplane in the morning.
Some people used to get quite aerated about the practice and insist that the offending article was removed before take-off.
Personally, I used to ignore them and by the time I got back to base I would probably have picked up four or five of them. At least it helped to remind me where I had been over the last week or so.
I think Muharraq used to slap a palm tree on and one unit had the rear end of a cat with the ar*ehole cut out (Sharjah or Masirah)?
The habit to me lay somewhere between "innocent fun" and "high spirits".
Edit: Thinking about it, I think the Masirah zapp was a turtle so Sharjah would have been the cat's ar*e. No doubt someone will put me right within the hour!