it will have to come...a standard form that both parties must sign...probably witnessed by a third party....a notary or JP...a signed agreement that both parties full consent to the forthcoming rumpy pumpy.
"I fully consent to my body parts being caressed by the second party and one full insertion may take place....etc etc "

Of course disputes will arise if you don;t read the fine print.

Every bedroom (or cottage) must carry a sign with the usual by-laws etc, that there are "no returns" or buyers remorse and every 'transaction' is final and no disputes will be entertainment nor correspondent entered into.

Every pub and nightclub and place of meeting..coffee shop, Annabels, restaurant must have signs stating "no responsibility taken if you pick up some trade here"...and so on etc etc

prove me wrong.

Stern dad to rake suitor: "Young man, have you slept with my daughter ?"

Rake: "No sir! Not a wink."