A head is part of most animal's anatomy. The brain is typically located in the head of most if not all species. Most Earth creatures and aliens have heads. Sometimes a person's head might hurt, and this is called a headache. Most species have one head, however, Fearians have three heads.
When the Super Friends leave the Junior Super Friends to hold down the fort at the Hall of Justice while they go to Washington, Marvin asks them what they do if there is an emergency, and Wonder Woman tells them to just use their heads.
Mary Marvel once told Captain Marvel that the only magic trick she wants to learn is the one that lets her shrink swelled heads. This of course was a jab at Captain Marvel, which embarrassed him, causing him to blush.