I was once asked to create a fully secure chat system prototype (the ui didn't matter) in 2 days. We ended up building a client in python (which I wrote) and it kinda worked and a c# backend that didn't really work.

1 hour before we had to present the project to some high up management we decided that we couldn't fix the bugs in the system.

So I came up with a cool idea. Why not use ssh?
So I set up a bash script that writes to a file and tail -f that reads from the file. That way you could chat securely with another person.
I made it 15 minutes before the presentation with no Internet working :) they said it was hacky but a cool solution they saw that day :p I felt happy and that I had to thank Linux for being there for me