We happened to be in the lab, so I pointed to a brown spot on the wall, made by a very powerful laser. After that, we referred to it as the brown laser.
I've seen many people try to argue that magenta doesn't exist, or isn't a color, etc., simply because it doesn't correlate to a single wavelength.
Regardless, what is he trying to say, then? That brown can't be understood because there is no such thing as a brown laser? My point remains.