Eating popcorn at the movies apparently makes people immune to advertising.
The idea behind putting a brand name in an ad is to imprint it on the brain so that people simulate the pronunciation the first time it's seen or heard.
The study published in the Journal of Consumer Psychology found that the act of chewing short circuits that process.
The researchers invited a group of people to a cinema to watch a movie preceded by ads. Half the people were given free popcorn, the other half a small sugar cube that dissolved in their mouths.
The ads had no apparent effect on people chewing popcorn. 
--Rob Archer