What nonstandard event would you like to swim?

Many swimmers I have talked to over the years have said that they would like to race some nonstandard event. Frequently mentioned examples are: a 75 butterfly, a 3-stroke IM, a 25 SDK, or a distance stroke event. Suppose you could enter some nonstandard events at a SCY meet, what would you pick? Perhaps a 2x400 breaststroke family relay? (Count me out on that one, but it does sound cool.) I thought about posting a poll, but it would be difficult to list all of the possibilities and I might miss some good idea, so I'm just inviting free-form response. Second question: would you travel to Philadelphia to swim it?