“What do you get when you cross a teacher with a vampire?”/“Lots of blood tests.”

A vampire riddle is:
 
Q: What do you get when you cross a teacher with a vampire?
A: Lots of blood tests.
 
The popular Halloween joke has been cited in print since at least 1986.
 
         
Google Books
696 Silly School Jokes & Riddles
By Joseph Rosenbloom
New York, NY: Sterling Publishing Company, Inc.
1986
Pg. 24:
What would you get if you crossed a vampire and a teacher?
Lots of blood tests.
 
9 July 1988, The Times (Trenton, NJ), “Good Humor,” pg. B1, col. 1:
Dave Allen asks: “What would you get if you crossed a vampire and a teacher?”
“Lots of blood tests.”
   
Google Groups: alt.tv.buffy-v-slayer
Vampire Joke
Tim Bruening
4/25/00
Q. What do you get when you cross a vampire and a teacher?
A. A lot of blood tests.
     
Google Books
1001 More Cool Jokes with Glen Singleton
BY Barb Whiter
Victoria, Australia: Hinkler Book Distributors
2002
Pg. 145:
What would you get if you crossed a teacher with a vampire?
Lots of blood tests.
 
Google Groups: alt.humor.puns
Puns of the Weak 11’29/02
Stan Kegel
11/29/02
(...)
What do you get when you cross a teacher and a vampire?
Lots of blood tests! (Hardik, 16)
 
Twitter
Peter Maurici‏
@BlokesLib
What do you get when you cross a teacher with a vampire?  A lot of blood tests.
12:31 AM - 19 Mar 2009
 
Google Books
Jokes about School
By Judy A. Winter
Mankato, MiN: Capstone Press
2011
Pg. 9:
What do you get if you cross a vampire and a teacher?
A lot of blood tests.
   
Google Books
101 Amazing Spooky Jokes
By Jack Goldstein
Andrews UK Limited
2013
Pg. ?:
What would you get if you crossed a vampire and a teacher?
Lots of blood tests!
 
Google Books
School Jokes For Kids 6
By Peter Crumpton
PeteyRF Creative
2015
Pg. ?:
What do you get when you cross a teacher with a vampire?
Lots of blood tests!
 
Twitter
Hallie A. Buckingham‏
@HallieBuck
“Powers Punchline” at Morning Meeting @EHSSouthport : What do you get if you cross a vampire & a teacher?” “A lot of blood tests!”
3:56 PM - 31 Oct 2017