1) A frequent user of the drug DXM (dex), which comes in cough syrup. If ingested in high amounts, DXM can produce hallucinogens and euphoric feelings.
2) Used in reference to a person who is generally spaced out, or oblivious to his or her surroundings.
1) My friend is such a dexhead! He just bought two more bottles of nyquil, and he's tripping on the shit right now!
2) That kid on my bus was just staring out the window when Ashley was trying to talk to him. What a dexhead.
A person stuck in the 80's...may have a mullet, tight jeans, sometimes pegged, comb in back pocket, listens to Def Leppard, and drinks Mountain Dew (in a glass bottle if available). Most often seen driving an old Camaro or Firebird. Watches Nascar and drinks cheap beer. The female form still has "mall hair" after all these years, curses like sailor, and still owns a Warrant CD.
This occurs when your father, or another man, or woman with a dildo, or your mum with a dildo, entered your mothers vagina while she was pregnant with you which led to the impression of the penis/dildo being left in your soft skull. This then becomes a feature of your skull. It can be useful for storing food or as a flower vase.