Haunted House Insurance
It sounds wacky at first but it makes sense. Haunted Houses are businesses and as such need liability coverage. Recently I heard a comedian on the radio talking about the insurance coverage they had to protect them in the event an attendee at one of their shows choked or was otherwise harmed by the laughter or a reaction caused by the performer.

This is the actual image taken from the insurance company's site.
The info below is from INPRO Insurance Group Site
Haunted House Insurance and Themed Attractions Insurance
Haunted House Insurance Brochure
We understand the unique aspects of your industry. Whether you operate a year-round business or a seasonal attraction, InPro Insurance Group can provide the comprehensive coverage you need to put your mind at rest. Our carriers specialize in programs specifically for Themed or Haunted Attractions and their unique insurance needs.
Haunted House Insurance Concerns:
Liability
We can provide affordable General Liability coverage for a wide range of attractions, including Haunted Houses and other Haunted Attractions, Pumpkin Patches, Christmas displays and other special events. Coverage can be extended to landlords or property owners as well.
Excess Liability
InPro Insurance Group can provide limits in excess of the General Liability limits noted above. You have the option of purchasing additional coverage
Volunteer Accident Insurance
Your volunteers are important to you. Let them know that by purchasing an Accident & Health Policy to cover them while they are helping to make your attraction a success.