Though repeating a ghost's name three times may summon him or her from ghastly alternate dimensions, it is far more polite to send a formal invitation. Encourage courteous interaction with the spirit world with today's Groupon to the Lizzie Borden Bed & Breakfast and Museum in Fall River, Massachusetts. Choose between two options:

• For $12, you get two adult historical-tour tickets (a $25 value).
• For $25, you get four family historical-tour tickets (up to a $50 value).

The Lizzie Borden Bed & Breakfast and Museum's tour guides weave a tale of intrigue at the haunted scene of an infamous unsolved murder, garnering recognition as one of MSNBC’s top 10 haunted homes in the United States and on The Huffington Post’s list of the world's creepiest places. Built in 1845, the Greek revival home has been restored to better approximate its appearance on August 4, 1892, when wealthy businessman Andrew Borden and his wife Abby were mysteriously murdered, perhaps by Andrew's youngest daughter Lizzie. Meander through haunted hallways on a one-hour tour of the bed and breakfast while shouting out trivia questions to entice helpful ghosts from hiding spots. Brave visitors can ascend creaky stairs to the third floor, where the ghosts of two children and a former caretaker are said to entertain themselves by flicking light switches on and off, and mischievously scrawling visitors’ ATM pin numbers on walls. Tours depart on the hour from 11 a.m. to 3 p.m.

Explore the gift shop for souvenirs such as an axe-wielding Lizzie Borden bobble head, a spooky addition to dashboards or an effective enforcer in the workplace. The Lizzie Borden Bed & Breakfast and Museum is also in the process of installing webcams in various rooms to enable online ghost hunting. Although not included in the Groupon value, the service will be offered to subscribers at least one night per week, provided ghosts have successfully installed software updates.