Are you sure that over the next few days, your consumption of pop corn and Coke is entirely under your conscious control ?
Are you sure that as this page was loading on your computer screen, there was no flashing subliminal message in the background saying EAT POP CORN and DRINK COKE ? Messages surreptitiously entering your unconscious mind, taking control of your behavior?

Claims that such things can happen made subliminal research controversial already in the Fifties. The possibility of covert propaganda and subliminal advertising was seen as both intriguing and frightening, causing media attention, public outrage and political intervention.