No worries man, just trying to figure out if you were looking for something specific or just kicking ideas around. Personally, I don't think a fridge would really have the right shape/volume (unless you lit it with CFLs maybe) With an HPS in there, your plant would have to be pretty short to keep it away from the heat stressing on the light I would think. As far as using a working fridge, you'd have to maintain a pretty tight balance between cooling the lamp and not chilling the leaves - that sounds like an extra layer of hassle to me.
Still, you never know till you try it.
I was at a yard sale a while ago and saw something that I thought would have made a good grow cabinet. In paint shops, paint cans are kept in a paint locker that has a 'fume vent' that's meant to exhaust outside. This one was a metal two-door cabinet with adjustable shelving and it already had a vent that would have been perfect for an exhaust fan. Something like that would go completely unnoticed in a suburban garage. The guy wanted $75 for this one - about 6' tall, 4' wide, and maybe 18" deep.