A British euphemism, for having sex in semi public places, like up on lookout ridge, being parked in a car in the woods, or also in viewing such activity. A sort of term, that encompasses exhibitionism, and voyeurism.
Supposed term was derived from men who would stalk (dog) couples who would park, or go into secluded spots, to engage in sex.
Others contend it derived from men who around bushes, claiming they were merely 'walking their dog' and not spying on the couple, though they didn't actually a dog.
Can refer to a form of stalking, that is however actually encouraged by many.
The Internet, text messaging, has led to an explosion of this particular type of sexual antics, not just in the UK where it was believed to have been started, but elsewhere, including North America.
In American English, the term may have a negative meaning, or be construed as being derogatory.
No such negative meaning is imparted in the British use of the term.
POODLING is a humorous take off on the word dogging, in that it refers to a couple engaging in sex, in a luxury vehicle, such as say a Rolls Royce versus a Volkswagen Beetle.