Question: What urban legend, involving a member of the Beatles, is a hobby of Gerben Moerman?

Context articles: Gerben Moerman
Crybaby Bridge
Urban legend
Paul is dead
Military stress card
Urban Legend in Limbo
Seven Gates of Hell
Very Together
Phantoms (novel)
Muhlenberg legend

Gerben Albert ("Gerben") Moerman (Schipluiden, 1976) is a Dutch sociologist who teaches at the University of Amsterdam (UvA).
 His specialty is sociological methodology, and he is member of the UvA group for Dynamics of Citizenship and Culture.
 He is considered something of an expert on breaching, and has drawn attention for a hobby of his--the Paul is dead conspiracy theory.
 In 2012, he was chosen as UvA teacher of the year; he was praised for being able to interest his students in the unpopular subject of sociological methodology, and for linking theory to society and continually surprising his students.
Crybaby Bridge is a nickname given to some bridges in the United States.
 The name often reflects an urban legend that the sound of a baby can be, or has been, heard from the bridge.
 Many are also accompanied by an urban legend relating to a baby or young child/children.
An urban legend, urban myth, urban tale, or contemporary legend is a form of modern folklore usually consisting of fictional stories, often with macabre elements, deeply rooted in local popular culture.
 These legends can be used for entertainment purposes, as well as semi-serious explanations for random events such as disappearances and strange objects.
"Paul is dead" is an urban legend and conspiracy theory alleging that Paul McCartney of the English rock band the Beatles died in 1966 and was secretly replaced by a look-alike.
The military stress card, a wallet-size card incorporating a liquid crystal thermometer, is the subject of debate whether or not its use by United States Armed Forces recruits is an urban legend.
 According to Snopes.com and "Stars and Stripes", stress cards can not be used by recruits in boot camp to halt training.
 But according to "Time" magazine, it was issued for this purpose by the Navy for recruits heading to boot camp at RTC Great Lakes.
 Whether urban legend or not, the purported use of them in boot camp is cited as evidence of the softening of U.S. military forces, degrading readiness to fight and even causing post-traumatic stress disorder in those who are exposed to the psychological rigors of combat.
Touhou Shinpiroku ~ Urban Legend in Limbo (東方深秘録　～ Urban Legend in Limbo , lit.
 "Eastern Record of Deep Mysteries" ) is a fighting game developed by Twilight Frontier and Team Shanghai Alice and published by Twilight Frontier.
 It is the 14.5th installment in the Touhou Project series and the first game to be illustrated by Moe Harukawa (who worked on "Wild and Horned Hermit" and "Forbidden Scrollery").
 It was released in May 2015.
The Seven Gates of Hell is a modern urban legend regarding locations in York County, Pennsylvania.
 Two versions of the legend exist, one involving a burnt insane asylum and the other an eccentric doctor.
 Both agree that there are seven gates in a wooded area of Hellam Township, Pennsylvania, and that anyone who passes through all seven goes straight to Hell.
 The location in question never housed an institution; the aforementioned doctor only constructed one gate, to keep out trespassers.
 Note this is private land subjecting visitors to trespassing charges.
Very Together was the only compilation of The Beatles' early recordings as The Beat Brothers released in Canada, released by Polydor Records—catalogue number 242.008.
 The cover, which features four candles with one snuffed out (a possible reference to the "Paul is dead" urban legend/hoax), was taken in 1969.
 One of just four albums to be released only in Canada; its scarcity in any condition is considerable.
 The content of this album is identical to that of the previously released European album "The Beatles' First" and the American album "In the Beginning (Circa 1960)" issued the following year.
Phantoms is a novel by American writer Dean Koontz, first published in 1983.
 The story is a version of the now-debunked urban legend involving a village mysteriously vanishing at Angikuni Lake.
The Muhlenberg legend is an urban legend in the United States and Germany.
 According to the legend, the single vote of Frederick Muhlenberg, the first ever Speaker of the U.S. House of Representatives, prevented German from becoming an official language of the United States.