“Where do vampires learn to suck blood?”/“Law school.”

A vampire riddle is:
 
Q: Where do vampires learn to suck blood?
A: Law school.
     
The lawyer joke was posted on the newsgroup alt.prisons on September 28, 1997, and has been printed on several images.
 
 
Google Groups: alt.prisons
Death Penalty as Deterance
.(JavaScript must be enabled to view this email address)
9/28/97
(...)
Where do Vampires learn to suck Blood???
Law school.
 
Google Groups: alt.humor.puns
[Fwd: Submit: Halloween Riddles]
Stan Kegel
10/30/00
(...)
Where do vampires learn to suck blood?
In law school… (From C C Jokes)
 
30 October 2001, Indianapolis (IN) Star, “Let it out,” pg. E3:
Where do vampires learn to suck blood? Law school.
 
Google Books
Lawyers and Vampires:
Cultural Histories of Legal Professions
Edited by W. Wesley Pue and David Sugarman
Portland, OR: Hart Publishing
2003
Pg. 243:
A tired joke remaking the law school rounds at the time of writing is: Q. Where do vampires learn to suck blood? A. At law school.
 
Google Books
The New Treasury of Gross Jokes
By Julius Alviin
New York, NY: Kensington Books
2004
Pg. ?:
Where do vampires learn to suck blood?
Law school.
 
Google Books
Redeeming Law:
Christian Calling and the Legal Profession
By Michael P. Schutt
Downers Grove, IL: InterVarsity Press
2007
Pg. 179:
Where do vampires learn to suck blood? Law school.
 
Twitter
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@welchlawllc
Welch Law’s Monday Funday:
Q: Where do vampires learn to suck blood?
A: Law school.
9:15 AM - 21 Nov 2016