According to Wikipedia, Namaqua Rain Frogs are less than 5cm long and are burrowing creatures that spend most of their time underground.
"When disturbed, these frogs have the ability to inflate their bodies dramatically as a defence mechanism to deter predators," Wikipedia also notes. Although it fails to say that these frogs then "squeak the cutest squeak you've ever heard in your life!!". Hmm. Maybe we should go in and edit that page...
(Via Viral Viral Videos)