A new yawn-activated vending machine has gone viral all over the internet. Machines like it dispensed free coffee and other treats after the patrons play a game of 'teacher says'.

At the Douwe Egberts airport, a yawn-activated vending machine utilized facial recognition software, and only supplied the drinks to the those who completed the task correctly. The machine was placed in the O.R. Tambo International Airport, and gave over 200 flyers a free cup of coffee.

Other machines had been sent out by other vendors, including a Coca-cola machine that charged the patrons hugs, and gave out cans of coke in return. The National University of Singapore had a note with the words "Hug Me" written in big letters.

Coca-cola, who's notorious for these kinds of machines, had another that demanded South Koreans to dance for the free soda drink. It tracked how the visitor copied dance moves for the songs that were played, and awarded them more if they were better on their feet.

A machine that detected smiles vended free ice cream of any flavors after they smiled at the screen. The Smile Happy machine measures the width of your grin and uploads the picture onto Facebook if the patron's smile is wide enough.

And last but not least, an Australian Fantastic Delites machine tested peoples' patience and willingness to obtain a free rice snack. In the beginning, the visitors were asked only to hit a button 100 times, which the escalated quickly until the ere told to bow down, do push ups, hop on one feet, and do the robot.

What would you be willing to do for free stuff?