Dogging/Exhibitionism

[jaime]

Best explanation I've heard is that the standard excuse for hanging around car parks after dark is "I'm just looking for my dog, officer".

Answering my own question, I have now found out how it came about. Back
in the '70s, some people in the UK started having sex outdoors, and
others followed them to watch, in other words they were 'dogging their
footsteps'. That's how the word came to be used for this undercover (and
delicious!!) practice.