Persons old enough to remember the 1950s will probably recognize the ad for a child's playhouse, which ran for years in a variety of comic books. Cracked.com has a report on 12 such "ads that taught us to be cynical," explaining what one really got if one ordered the product. In the case of the playhouse, the product was (not surprisingly) made of cardboard.
It's interesting to note the price of $1.00 (80c when purchased in bulk). This was of course in the days when the U.S. dollar had some value, and the shipping cost of 25c was actually substantial at a time when first-class rates were 3c. The report also discusses "hypno-coins," 7-foot-long nuclear subs (also made of cardboard), monkeys-in-a-teacup (those were - unfortunately - real), and, of course, the unforgettable "x-ray specs."