Accidentally wrote a 2GB 'nohup.out' file when I forgot I had a script running as nohup in the background without redirecting STDOUT and STDERR to /dev/null.

Basically, I forgot to prevent saving the output of my program to a file, and it created a massive file because of it.

2GB might not seem like much, but this was on a server with ~5GB free space left. Could have been worse had I not caught it sooner.