1 definition by idiom police
In the gym, a meathead is the guy who only does mirror exercises and looks at himself frequently to see his development (imaginary or real). A mirror exercise is for a muscle that you see when you look in the mirror. These are chest, biceps and abdominals, and nothing else.
Go to any gym and you will see lots of guys (meatheads) like this. Hint: They are always in front of the mirrors.
by idiom police October 27, 2011