Really?! 204 comments about the etymology of the 'hash'-whatever?!
Back to the topic at hand. I confess that in the early 80's I was known to make use of the debugging tool within CICS (name and author escapes me at the moment) to write over the shared control blocks with garbage, bringing down the entire control region.
This was necessary because I was ready to test my program, and I didn't want to wait until the Sysadmins cycled CICS overnight, which at the time was the only way to refresh the binaries in the load libraries.
I was never caught (by the sysadmins - my fellow developers were in cahoots with me since they needed their stuff reloaded too).