I was recently watching Tom and Jerry with my kids and there was a particular scene where a battered Tom says the phrase “Don’t you believe it” in a rather creepy tone. This line used to creep me out as a young child.

You can see the clip here:

https://www.youtube.com/watch?v=a9U_C_q6WcU

The line also pops up in at least two other Looney Tunes episodes, including a Bugs Bunny episode. So this made it seem like a cultural reference of the time. And of course, I had to figure it out.

There are many theories online:

The Answer

Largely thanks to discussions with my grandfather and from reading the day3media.com culture page, I found the answer. The answer lies in an old 1940s radio program called, coincidentally enough, “Don’t You Believe It!”. This radio show was kind of the Mythbusters of the day and this was their catchphrase.

Here’s an excerpt from Day3media.com’s culture page. Listen to an excerpt from the January 4, 1947 episode of the radio show: DontYouBelieveIt.mp3