Because they croak a lot!
Because a frog croaks all the time but a cat only gets to croak nine times!
Because she wouldn't rub it rub it. (blame Happy International Bacon Day)
Because they have a lot of grey matter!
Duh. Cause he's da foe.
Brucism
A frog -- it croaks every night.
In a croak of gold at the end of the rainbow!