An insurable event. (source)
Believe it or not, a London based firm has sold more than 30,000 alien abduction insurance policies throughout Europe. Of course, you’ll need to provide proof of the occurrence to file a claim.
That is from Geico, and there are many more obscure types of insurance at the link. They celebrity-body-part ones are great. For the pointer I thank Weakonomics, and there is also more here.