When you inconvenience others to save money or go to moderate lengths to justify either one of these behaviors.
Frugal people don’t save money by burdening the people around them with their expenses. Cheap people have no problem doing that.
If your frugal actions are making the people in your life embarrassed or uncomfortable, you’ve gone too far
I knew a guy once who’d buy a package of lightbulbs or batteries, take the fresh ones out, replace them with the dead ones, then return them to the store claiming they didn’t work and get his money back