“Witches” sounds like “which is.” “RT @timbuckteeth: Halloween is only good for one thing. Which is….” was posted on Twitter by Darcy Moore on October 31, 2009.
     
“There’s one thing I don’t like about halloween which is” was posted on Twitter by Gary Delaney on June 25, 2010.
   
A conversational version was posted on Reddit—Dadjokes on October 28, 2017:
     
I said to my son, “There’s only one thing about Halloween that scares me.”
He asked, “Which is?”
I replied, “Exactly!”
 
           
Twitter
Steve Wheeler
@SteveWheeler
Halloween is only good for one thing. Which is….
4:17 AM · Oct 31, 2009·Twitter Web Client
   
Twitter
Darcy Moore
@Darcy1968
RT @timbuckteeth: Halloween is only good for one thing. Which is….
4:19 AM · Oct 31, 2009·Twitter Web Client
 
Twitter
Paul Richardson
@paulbrichardson
RT @timbuckteeth. Halloween is only good for one thing. Which is…......
12:49 PM · Oct 31, 2009·Twitter Web Client
   
Twitter
Gary Delaney
@GaryDelaney
There’s one thing I don’t like about halloween which is.
3:59 PM · Jun 25, 2010·Twitter Web Client
   
Twitter
Sandu Ionut
@ionuvich
My mate said there’s one thing he hates about Halloween…“Which is?” I asked.. “Yeah,” he replied, “they freak me out.”
1:42 PM · Jun 26, 2010·Twitter Web Client
 
Twitter
Shit Jokes
@ShitJokes
My mate just said “there’s only one thing that a scares me about Halloween”
I asked “which is?”
“Exactly” he replied.
11:03 AM · Oct 31, 2015·Twitter for Android
 
Twitter
Paul Eaton
@GannetPaul
@ShittierJokes My mate said “There’s only one thing that about Halloween that scares me.”
I asked “Which is?”
“Exactly” he replied.
4:59 AM · Oct 27, 2017·Twitter for Android
 
Reddit—Dadjokes
Posted by u/madazzahatter October 28, 2017
I said to my son, “There’s only one thing about Halloween that scares me.”
He asked, “Which is?”
I replied, “Exactly!”
   
Twitter
Stéph
@CoupedesPotats
There’s only one thing I don’t like about Halloween… Which is…
~ Gary Delaney
10:21 PM · Dec 4, 2018·Twitter for Android
 
Reddit—Oneliners
Posted by u/SamBalotelli June 25, 2019
There’s only one thing I don’t like about halloween, which is..
 
Reddit—Dadjokes
Posted by u/Rav4xle June 4, 2020
My buddy said ‘There’s only one thing about Halloween that scares me.’
I asked, ‘Which is?’
‘Exactly’, he replied.