Not a stock, but I downloaded robinhood sometime in the summer 2020 while I was an intern. Never put money into it, but instead played around with the money I got from the free stock until I had ≈50 dollars. (Stocks only go up so it was easy). Then I got bored of it and threw it into doge at ≈.002 and forgot about it. Whenever the first dogecoin rally was happening I remember that I had some and got on my account and immediately sold at .06 for ≈$1400. Money really helped with living expenses in college.

Naturally I thought I was a savant. A couple months later it would have been worth like 14000. Lost some sleep over that one. Don't have my robinhood account anymore so I can't get the exact numbers and dates. Pretty sad that I peaked so early in my trading career.