All good guesses
![Big Hug :bighug: :bighug:](/data/assets/smilies/bighug.gif)
..
I knew it was i tough one...
But heres the story :
The Califonian Tree Frog is famous because in the early days of "Talking Movies" the first foley artists needed a frog croack, and basically just stuck a mic out the window and recorded the local frog.
and ever since this single croack has been used universally as the "croack".. so when any frog sound is heard in movies or tv.. it's properly this guy, even though not 2 frogs sound the same