Oh sh*t. It all makes sense now.

I'm kind of ashamed to write this, but I had never realized what "radio button" actually means.

I grew up knowing what they were (I was born in the 80s), but English not being my primary language, I never considered that "radio button" might mean "the kind of button you have in a radio". And I never felt the need to look for a definition :)

(are you done laughing?)