I don't go to Walmart much anymore, mostly because the toy department seems to be shrinking. That might be the only reason I noticed these surprise toys, though. They were in the stuffed animal aisle, which I don't usually spend much time in, but last week I wandered through because I'd quickly run out of other things to look at.
The toy I found is called a FlipaZoo. There are many varieties of these "flippable" stuffed toys, but the ones that caught my eye are called Flip Box Surprise: