You say source, I say narrative. While not wrong to suggest many Urban Dictionary definitions are either jokes or in use by nobody but the poster, the English language is not and probably never has been at rest. Urban Dictionary is a pretty large destination for recording slang as it develops. Especially in this case, where it was made popular by the "He Boot Too Big" meme:

https://knowyourmeme.com/memes/he-boot-too-big-for-he-gotdam...