Setting up or to Set up a public but
anonymous meeting for sex, Setters usually wear a mask and hood/hat, they
don't generally speak in person and the participant receiving waits leaning/bent forward over a wall or fence (Somewhere out of public eye) etc and puts something of an agreed colour hanging out of their back pocket. This allows the other person to simply walk up behind them and initiate sexual contact.
The setter is the top and the spark is the bottom.
Participants can be M/M, M/
F, T/M, T/F
F/
F. (OF LEGAL AGE!) A very UK silent practice.