In reality, we'd probably decline. But a fairly safe alternative is to play along, keeping an eye on their demeanour. If they make a statement and are sort of looking at you to see how you react to it, run like the wind. Yeah, I'm up there on the paranoia scale too.
If you don't mind the fact that they would know you two are 'wild' enough to even attend such a party, I'd say go. But I'd suggest that you behave yourself. Don't do a lot of drinking. Don't screw anybody...especially not the friends you went with. Pretend you're there to observe
and take the opportunity do some networking. Flirting would probably be ok. If you're serious about someday playing with this vanilla couple, and they truly are new to swinging (they might be playing dumb, too!), I wouldn't go too overboard the first night. Don't want to scare the hell out of them.
