"Thou shalt not covet" comes to mind.

Very nice! I never tire of seeing that.

I have two man-caves: my elder son's former bedroom (about 10 x 11 ft.), which I quickly commandeered as a much-needed home office for my consulting practice the minute he moved out, and the 2-car garage I had designed and added to the house a couple of years after his little brother came along. I have to share the latter with the cars, which I push out of the way when I need to work on cars, bikes, electronics, carpentry, whatever. I also make heavy use of bicycle storage hooks (seems appropriate) screwed into the rafters, so that I can hang bikes and spare wheels above the cars.

After adding the new garage, we had converted the original one into a family room / bonus room and later "teen room." My wife, a pictorial artist (oils and water colors), now has it as her art and ballet studio / woman-cave.