Had a guy once come into work who claimed he’d invented an aftermarket engine thinger that would let all current engines run on biodiesel, effectively solving the world’s energy needs. Said his neighbours were annoyed at him because he’d got it all rigged up in his garage and the local taxi drivers were queueing round the block for it.
I said ok, sounds fantastic, just write up some technical details and maybe a few sketches, send them through and we’ll get started on your patent application.
Never heard from him again.