i have been there quite a few times and had my first and only experience so far , i was parked next to a car with a couple in , she was giving him a bj and they had window open , at the time i was a bit unsure what to do i so wanted to get out of car and stand by window but did not want to break any rules
so i sat and watched , they carried on for a while and did not seem to mind me watching , i really regret not getting out of car ! should i have got out or did i do the "right thing " and just watch from my car ?
It's never easy knowing what's right or wrong! From our point of view it depends how far along the line we are, from our point of view if you had got out straight away nothing would have happened, after we had got down to a little 'play' if you had got out of your car and stood by it, (from your point of view) are they still enjoying themselves? fine then treat it like 'what's the time mister wolf'
if you move closer and they stop, your to close! return to your car and start again when they start again. It is never easy to get it right, but slowly slowly catchy monkey is always good to remember.
serindipty wrote that you was not intivited over, not all couples do, we don't ever invite or flash any lights except by accident, evey couple is different so just enjoy and learn as you go along