You know those birds that hang out by the ocean, and grab your sandwich if you aren't paying attention? Those are gulls, also known as sea gulls. Gulls are found in every continent, including Antarctica.
The noun gull has two very distinct definitions. Gulls are shore birds, of course, but lesser-used meaning of the word is "a person who is easy to fool." Your little brother might be a gull if you can trick him into doing your chores along with his own. You may know the related word gullible, which describes a willingness to believe anything, without questioning whether it is true.