What happened is arguably more stupid: by filling up the disk, 1) they definitely noticed, 2) I couldn't get what I wanted, and 3) I couldn't clean up the logs after it. Thankfully I had covered up my steps (or, more probably, the sysadmin was ashamed to see he had been hacked and chose to fix it and say nothing).
Reminds me of something similar that happened to me once a long time ago.
I hacked into a server. I wanted to take a copy of everything so I made a tar of / to wget it to computer later. Only that the disk was at >50% usage so I filled it by making the tar file. Everything stopped to work with 0 bytes left of disk space (I wasn't root) so I kinda bricked the machine. I had to walk away in shame.