http://lorempixel.com/ - does something very similar, but you can tell it the size of picture you're looking for and all the images are creative commons.
I think it just gets the first image from google images with your given keyword. You can also get the second, third, etc by doing http://kittens2.jpg.to, http://kittens3.jpg.to
Unfortunately, escaped characters aren't allowed as subdomains so you'll have to hardcode them as a switch/ifelse chain which returns appropriate searches (eg . => "fullstop.jpg.to")..
"jpg" "gif" "png"
"face" "photo" "clipart" "lineart"
"black" "blue" "brown" "gray" "green" "orange" "pink" "purple" "red" "teal" "white" "yellow"
"huge" "xxl" "xxlarge" "xl" "xlarge" "l" "large" "m" "medium" "s" "small" "xs" "i" "icon"
"r" "random"