The other night my 7 year old son and I were outside, when we noticed a strange animal sound. We could not figure out what it was, but my husband guessed that it was a frog and he was quite right.
I was quite surprised that a frog could sound like that as it was nothing like your nice, normal, ordinary "ribbit ribbit" or "glub glub".
Here is a link to some very different frog sounds... some I hope never to hear if I am ever lost, alone in the woods at night (And I also really hope never to be lost, alone in the woods at night period). Our frog turned out to be a gray treefrog.