“How do zombies do well in school?”/“They eat lots of brain food.”

A riddle about zombies is:
 
Q: How do zombies do well in school?
A: They eat lots of brain food.
 
The joke has been cited in print since at least 2012.
   
 
Twitter
David Murray
‏@SasquatchDave
Why do zombies eat brains?  Because they’re the ultimate brain food?
2:34 PM - 24 Aug 2009
     
Twitter     
Andrew Heisler
‏@andrewmheisler
What do zombies eat before an exam? BRAIN FOOD @ianfrye #hahaha
8:51 AM - 18 May 2012
 
Walking Dead Forums
Zombie Jokes.
rabscuttle1
08-27-2012
How do zombies study for tests?
By eating lots of brain food.
 
Twitter
SCAD HvZ
‏@SCADHvZ
Q: How do zombies study for tests?
A: By eating a lot of brain food!
Good Luck on finals players!
2:02 PM - 21 May 2014
 
Twitter
Kristin Whitehead
‏@KKreations11
Evsters has a joke…
What do zombies eat before a test?
ANSWER: Brain food!
(He was quite proud of himself for that one)
1:23 PM - 28 Jul 2014
 
Twitter
Escape From Zombies
‏@EscapeZombies
Bad Joke Theater:  Q: How do zombies do well in school?  A: They eat lots of brain food!  Come back tomorrow for another HORRORable joke!
11:04 AM - 13 Oct 2015
   
YouTube
Golden Apples | Halloween UHShe Episode 6 | UHC
LDShadowLady
Published on Oct 21, 2015
(...)
COMMENTS
BugSplat
What do Zombies do before a test?
The eat a lot of Brain Food! xD
 
Twitter
Escape From Zombies
‏@EscapeZombies
Q: Why do zombies do well in school?  A: They eat lots of brain food!  Come back tomorrow for another HORRORable joke!
4:50 PM - 30 Jan 2016
 
Minecraft
Bianca Arcenas September 3, 2016 at 1:33 am
What do zombies do before taking a test?
They eat a lot of BRAIN FOOD