💁♂️: A common belief was that this phrase stemmed from a law that a husband is allowed to beat his wife with a stick no wider than his thumb. However, this law was found to be true. the earliest use of this phrase was back in 1600s and the origin is still unknown.
The logo for the video game Fallout has a cartoon character (Vault Boy) with his thumb out and one eye open because he is measuring the stem of the mushroom cloud with his thumb to determine if he needs to start evacuating the area
