I think these old World War I posters illustrate both advertising and zap.
I would have thought that the next poster was a little risque for the early 1900s but it has been said that all is fair in love and war, although I don't agree with that saying. It almost looks like the woman is wearing her undergarments or at least the type of undergarments worn in the early 1900s.
From an historical perspective it interests me to see the advertising techniques of the U.S. war office during World War I.
The reflections made it hard to photograph these posters. In case you can't read the last line on the next poster, it says: leave nothing on your plate.
I've never thought it made sense to tell children to think of people that are hungry to encourage them to eat everything on their plates. It does make sense to tell them that eating less of certain foods helps if those foods will be sent to the people who need those foods.
Click for Sandy's Zap Photohunt and/or click for Gattina's advertising photohunt.