Two things I did that were very fun:

1. School blocked a lot of popular flash game websites. My friends and I downloaded a bunch of flash games and threw together a website that we hosted on our chromebooks using '200 OK - Webserver for Chrome' or something. It was just a bunch of janky HTML and CSS, but we got it working. The school didn't block it because it was on the local network. We handed out slips of paper to our friends with the local IP address of my laptop. At one point someone made a Google Site with a link to the local address. It was a hack, but playing RUN 2 on your chromebook during social studies in 5th grade... man, those were the days.

2. Around that time one of my friends stumbled across crouton, a way to run Linux on a chromebook in parallel with ChromeOS. After a lot of trial and error (didn't know what bash was at the time), we were able to get Ubuntu installed. I remember downloading Blender and trying to do a fluid sim, which was super slow. I was able to render the first 20 frames of a domino and fluid animation using Cycles, which frames I still have sitting on my hard-drive somewhere to this day.

Some of my first hacks, older me is surprised how much younger me was able to get done given how much younger me didn't know.