This is actually an interesting legal problem. How would two * willing * co-workers initiate casual sex on a business trip? Certainly this situation has cropped up before! Neither would want to risk their careers on making an unwanted advance toward the other!

Presenting a coworker with a long legal document giving consent to be propositioned, signed with a notary present of course, wouldn't work. It would be sexual harassment to even present the contract for consideration!

They would have to use something like Tinder where they could be both unaware of the others interest until both parties had signed the legal agreement consenting to be propositioned by the other. They would then be directed to do some sort of custom secret society hand sign in the others presence to verify that they had actually consented. The hand sign would be innocuous when seen by someone who hadn't actually signed the contract via the app and seen the secret hand sign the other would display to acknowledge they had signed the contract.

The next billion dollar startup idea?! A cross between Linkedin, LegalZoom and Tinder. The idea would at least make for a hilarious episode of "The IT Crowd" or "Silicon Valley".