Fun Windows trick

I just discovered a funny thing you can do with Windows' environment variables. Did you know that it will allow you to create a variable with "\" in the name, and that it will not be able to distinguish that "\" from an ordinary file path separator?

Try this:
1) Go to advanced system settings then go to the Environment Variable dialog.
2) Create a new user variable - call it "some\variable" and give it a value "123"
3) Create a folder anywhere on the system - call it "%some"
4) Within that folder, create a file - call it "variable%.txt"
5) Try to access that file by typing in it's path in explorer or cmd - e.g. "C:\%some\variable%.txt"
6) Windows will say "Windows can't find 'C:\123.txt'. Check the spelling and try again."

EDIT: Even funnier, you can actually call a file or folder "%temp%.txt"