A smol brag is when a girl feels the need to let you know how smol, cute and truly unique she is! To her no one is as smol as she is, she wants to be admired for her smolness.
(example 1)
Kenna - " I'm such a smol bean i can wear kids clothes, i'm only 4'11 !"
(example 2)
Georgia May - " How are my feet a size 2.5 at 25 years old. And when did they suddenly shrink? #smolgirlprobs "
Shoe sales girl - " Don't smol brag, peoples feet don't shrink as they get older they actually get bigger! "