Long ago, when I worked in a computer room on a shift with a dozen or so other guys, we used to play with the intercom which was just a button on the phones to go PA, and several of us would be on at the same time doing these calls to sound like frogs:
ankledeep (high voice)
kneedeep (medium voice)
deeper (medium voice)
ribbit (medium low voice)
rain (deepest voice)
Did you ever do such foolishness?
What other frog sounds do you use?