I guess this really makes a lot of sense if you consider that they tend to make a lot of noise before rain storms. Some Australian aborigines and Native American groups believed that frogs were the bringers of rain. In India, frogs were believed to personify thunder in the sky. Frogs and Luck Sometimes, cultures associated frogs with good and bad fortune. In Japan, frogs are the symbols of Good Luck.
Some myths are less favoring to frogs and toads.
I read this in my cool book called Frogs. Check out this and other neat books in my Recommended Reading list. Some say that you get warts from touching frogs and toads. Frogs have slimy skin to stay moist when it is dry, and toads have bumpy skin to help camouflage them in their habitat. Another story I've heard was that American soldiers adopted the nickname for the French during the World War II because they ate frog legs and hid well when camouflaged.