Google files patent to let you unlock your phone by grimacing at it
The patent covers technology to match at least one facial landmark between the pre-funny-face and during-funny-face images. If Google develops the technology, we can prepare ourselves for grimacing public displays and associated melodroidma. 
Read more: Google files patent to let you unlock your phone by grimacing at it
Story added 12. June 2013, content source with full text you can find at link above.