Unusual Party Invites

I live in a newly established neighboorhood, where people are still getting to know one another. The other day I recieved an invitation to an `adult` party, where there will be an array sex themed novelties and the like. I feel very awkward and confused. How should I respond to this, being that it is my next door neighbor, someone I say `hello` to everyday. I feel funny when I see her husband or her outside at the mailbox or grocery store. I feel that this was in poor taste and bad judgment. What should I do? Help!?