Ah sounds like a green tree frog? Does he look kind of like this? http://www.netstate.com/states/symb/amphibians/images/la_green_tree_frog.jpg
We had one we called him lucky, respectively, he got attacked by our cats and lost 1 leg and 1 eye so he was lucky to be alive. Had him about 3 years before he finally died. He used to croak at night. I also had a barking tree frog (go figure) that would blow up really big around it's throat and "bark" at night. I think it is either a mating thing or just a form of communication.
