"Buzz, your girlfriend! Woof!""
―'Kevin, seeing a picture of Buzz's girlfriend
She was shown in a picture when Kevin was looking through Buzz's stuff on his first day alone. She wears headgear and had a shocked expression. Kevin was disgusted upon seeing her picture and put the picture down in a hiding position.
The "girl" in the picture was actually the son of the film's art director made up like a girl, because director Chris Columbus thought it too cruel to humiliate any real girl in such a fashion.