Skull and Bones, the secret society at Yale University, is warning of an impostor who has called some students purporting to recruit them and then asking them to complete a humiliating challenge.

The campus society has figured prominently in books, films and conspiracy theories. It dates back to the 1800s

Its secrecy has fueled the public's curiosity about a group that counts former Secretary of State John Kerry and both Presidents Bush among its past members.

Students on campus said last week was "tap week," which is a time when rising seniors are asked to join the secret society.

In recent days, an email to the junior class said an anonymous caller exploited the mysterious nature of the group and student desires to join it.

"One of my roommates actually told me they’re asking the initiations that those pranks were asking were some very egregious things," said student Byron Daniel.

A Yale spokesman said “Within the past few weeks the Yale Police Department has received three complaints of harassing telephone calls from an individual purporting to be from Skull and Bones. These cases remain open.”

Skull and Bones said in a notice sent through Yale's student government that it would never ask recruits to engage in uncomfortable or criminal acts.

Anyone with information on the imposter caller is asked to call Yale police or the college dean.

Copyright 2018 WFSB (Meredith Corporation). The Associated Press contributed to this report. All rights reserved.