You see a lot of these ads in comics. Promising lots of crazy fun. Lets take a look a few that stand out for me.
Throw you Voice
What you received for $0.25 was a swazzle, a device made of two strips of metal bound around a cotton tape reed that you position between you tongue and the roof of your mouth. Right...I wonder how many kids choked on that one...Danger!
From Wikipedia: The lenses consist of two layers of cardboard with a small hole about 6 mm (.25 inch) in diameter punched through both layers. The user views objects through the holes. A feather is embedded between the layers of each lens. The vanes of the feathers are so close together that light is diffracted, causing the user to receive two slightly offset images.
Monster Size Monsters
I think these were sheets of printed polyethylene. " so life-like you'll probably find yourself talking to them"???? ...
Secret Spy Scope
Karate! Home study course.
Only a kid would believe they could learn Karate on their own in the comfort of their bedroom or garage.
Skin Head Wig