Dowlhead is a word used to describe your friends absurdly incoherent behavior. Also dowlhead can be used to describe a "muscle head" who spends more time checking himself out in the mirror at the gym than actually working out.
Scenario 1:
You are making zero since you freakin dowlhead
Scenario 2:
Guy 1: Oh my god dude, checkout this fag looking at his abs in the mirror
Depending on the rest of the sentence i.e., context; depressing, depression, or depressing event or situation. Bummed out, bummer.
1) Aw dude ... you're giving me a down head! (You are depressing me)
2) Sorry to hear that ... that's a down head. (That is a depressing event, or bummer)
3) I'm in a down head (bummed-out mood ... though it is rarely used in this way, I would certainly understand what the person meant if s/he said this)