For some reason today I was struck by one of those memories from being a young teen that made me really "what the fuck...?" at my thoughts and lack of common sense.
I can't be the only and I'm looking forward to laughing at hearing yours 
Mine was from age 12. I've always been a bit of a hairy girl in that I'm dark haired and now have a pcos diagnosis so, without any of my own, id use my dad's razor to shave my legs and pits (I know, I know...) one day I looked at my brows whilst sat in the bath and thought they needed shaping too...
So I tried and went badly wrong and took a full chunk out of the brow hair. I tried to even it up and sort it out but ended up with no eyebrow whatsoever over one eye.
Not having any make up back then and no money to buy any I wondered wtf I was going to do. Clearly the only thing to do was shave the other off to match and keep my fringe over my forehead and eyes. I assume my thought was that they'd grow back evenly together and 'not be as noticeable' (!)
You don't need me to tell you that wasn't that easy. My friends were the same in that they had no make up too back then so I just had to wait for them to grow back. Even the staff teased me about it. I still remember my maths teacher at the time grabbing my arm after I'd refused to show them when she asked and not letting me slink out the class until she saw and laughed at them. 