Vault Boy has long been an important mascot for the Fallout franchise, and this is once again the case in Fallout 4. The character's smile and iconic thumbs-up pose seem to clash with the post-apocalyptic nature of the series, but there may actually be a deeper meaning behind the Fallout thumbs-up than a lot of people realize, and it's one that's much more connected to the series' universe than first meets the eye.

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Despite it appearing countless times throughout them, the games never really reference the Vault Boy thumbs up directly, leaving many players to speculate about its true meaning. However, the first episode of Amazon's Fallout TV series seems to confirm what some had suspected all along; effectively canonizing a popular yet hotly contested fan theory.

What Does the Fallout Thumbs Up Mean?

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A closer look at Vault Boy shows that he's closing his left eye and looking at his thumb with his right. Supposedly, the reason for Vault Boy's thumbs-up pose is to see how safe he is in the face of an atomic blast. It's said that if a person does this and the resulting mushroom cloud can still be seen from behind their thumb, they're within the radiation zone and should evacuate immediately. This is explained to Lucy by her father near the beginning of the first episode of Amazon's Fallout show and put into practice by the pair soon after.

Does Fallout's Rule of Thumb Really Work?

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Sadly, although the Rule of Thumb is taught in some hazmat courses, it's generally used to determine whether paramedics and first responders are a safe distance from smaller explosions; not nuclear blasts. Over the years, countless sources have debunked the idea of using this method to remain safe in the aftermath of an atomic bomb. This includes series creator Brian Fargo, who when quizzed about the origin of the Fallout thumbs-up on Twitter, responded with "The vault boy simply has a positive attitude."

fallout 4 box art
Fallout 4

Developer(s)
Bethesda
Publisher(s)
Bethesda
Platform(s)
PC , PS4 , PS5 , Xbox One , Xbox Series X , Xbox Series S
Released
November 10, 2015
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