An MH (non-conversion) bulb in a HPS ballast?

I was surfing Google and came across a thread on a another forum and a guy said that he uses a MH bulb in his HPS ballast with no problem for vegging. Sounds kinda fishy to me but is it possible? Better yet has anyone ever tried it? I'm not fuckin up ballast or burning down down the castle, but its one of those things I had to confirm with yall.

i dont think it would work :\

I forgot to post the link
HPS for Vegging

My impression from reading the thread is that it works but it's hard on his ballast. He says he replaces his every couple of years. I think it would depend on the ballast how well it works. I wouldn't recommend it if your ballast isn't designed for it. I have a digital Lumatek ballast and it's designed to run regular MH bulbs as well as HPS.

yeah i wouldn't it can't be good for it

figured that! Thanks guys