| Chris J.J. |
Making it a joke is a good way to diffuse the situation if players are really seeking sexual roleplay that makes you or any of your players uncomfortable.
I GMed for a group of my friends, and this has come up a few times, as there are two married couples who wanted their characters to be together as well, but surprisingly didn't start them out that way.
For the most part we handled things "offscreen", but at the beginning there was a point where they wanted to roll for it to see if the husband could seduce the wife and then they wanted to know how satisfied they were with each other's performance.
He was a half-orc, she was a half-elf. I had him do a Diplomacy/Bluff check against her Will save. For the deed itself, he rolled Performance, she rolled Handle Animal. The whole table busted a gut laughing at that one.
Also, it can be a good mini plot hook. Have a jealous lover or honor-bound secret admirer/stalker break in before the deed is done. Another idea is to have the town's local laws be very prudish and have the character jailed for "private indecency." No sex within the town lines, or some such.