In 1960, an enterprising inventor named Harold C. Tifft patented the "portable shield," a device that would ostensibly protect its user from radioactive fallout until help arrived. Or if help arrived. You're sporting your coffin on your back!
Here's how Tifft describes his ghoulish, anti-nuke carapace:
In one specific embodiment, this invention contemplates a portable and vertically adjustable shield which will protect the wearer against heat, atomic radiation, atomic fall-out, and flying debris in the event of nuclear warfare [...] A further object of this invention is to provide a shield for the body which, in addition to being portable, also can be readily adjusted by the wearer so as to permit him to run from one place to another and yet still have a substantial measure of protection on the upper portion of his body.
As you can see from the above illustrations, the user either A.) sucked face with wall until someone noticed; or B.) laid prone on the ground like a speed bump, the doomed final tenant of a one-room capsule hotel. I guess you could scoot around like a slug, but I'd like to maintain my dignity during the apocalypse and die on my feet (thank you very much). Also, Tifft wanted to line these things with asbestos, but that's the least of your worries during an atomic attack.
I suppose I can see the utility of such a suit in an emergency, but if nobody comes to assist you, you'll feel like a ripe jackass, riding out doomsday trapped in your casket. Better to just pull a Crystal Skull and jump into the nearest Frigidaire. You'll probably asphyxiate, but at least you'll be going out Indy-style.