What would happen if every unemployed person in the nation all at once stopped looking for work for one month?

[Ricky Bobby]

if every unemployed person in the nation stopped looking for work for a month, as already has been noted, they would cease to be counted as unemployed. I guess then, for a while, there would be 100% employment (though in the normal turbulence of the job market this will be only a brief phenomenon before some of the previously employed became the new unemployed - unless of course you mean that for a month period even the newly unemployed don't look for jobs either).

In terms of the supply and demand perspective you mentioned, with 100% employment the economy would start overheating. Competition for labour would mean that wage pressures would increase, which would increase inflationary pressures as well. Increased inflationary pressures would in turn create more wage pressures as employees find their wages can't buy as much as it used to.

In the meanwhile, all the unemployed people who are staging their boycott will be getting poorer and poorer in a society where the prices are rapidly rising. The classic insider/outsider scenario. All the gainfully employed will therefore be very happy if the unemployed were to pursue this route.