I read a review of couch fucking in a magazine,
Maxim or Loaded. The reviewer also tested other
forms of masturbation such as giving yourself a dead arm,
putting on nail polish, and pretending it belonged to someone else
(a favourite of sailors we are told), but back to couch
fucking. The reviewer mentioned that if you have a couch
with big cushions you can wedge a plastic bag filled
with mince meat between the cushions (don't forget to
warm the meat in the microwave). Insert into
plastic bag and proceed until completion.
I can't remember how high this method rated.