What does Boxing Day have to do with boxing?
wisdom tooth wis·dom tooth (wĭz'dəm)
The third molar tooth on both sides of each jaw that erupts from the 17th to the 23rd year.
Note: These teeth are associated with wisdom because they appear during the late teens or early twenties, when a person is physically mature. Often, the wisdom teeth may not rise above the gum line, but remain impacted in the jaw, causing inflammation. If this impaction occurs, or if they pose a threat to other teeth, the wisdom teeth may need to be removed.