I'm not sure if this will count, but I put all $700 inherited from my dead Grandma, a full paycheck, and some extra cash from my parents into building an excellent gaming pc.
Also, I have to mention my prom night because everyone else brought it up. I didn't go my Junior year. Instead, I had a gaming party over at my house with five close friends. I called it the anti-prom and it was badass.
I decided to go to my Senior prom because I figured that I'd regret not going in like 50 years or something. I wore a tuxedo t-shirt, and a suit jacket borrowed from my dad over it (because there was a dress code of sorts) jeans, a spike collar, and a pink cowboy hat. I drove my friend and his date, but his date got along much better with me because he's apparently scared of women. We stayed for about an hour, left because it sucked, and spent a few hours at a local console LAN center playing Halo 2 (yuck!). Still it was more fun than the prom, in mean no one was even dancing. What a load of crap!