The douchebag version of yourself; someone who resembles you, but is a douchebag. (From the slang "DOUCHEbag" + the German "doppelGANGER" meaning someone who resembles someone else.)
Tyrone is a great guy; Robbie looks like Tyrone, but Robbie is a douchebag. Robbie is Tyrone's douchelganger.
A douchebanger is a girl who repeatedly has sex or hooks up with complete douchebags. She may be slightly aware or completely in denial. She does it on a regular basis, and has not been well exposed to other types of men... normal guys who have manners, normal taste in clothing, and know how to treat a lady
"Wow she's such a douchebanger, I can't believe she's going home with that douche-sack." Girls who usually have low sel-esteem or think they know what is "cool" sleep with douchebags. Therefore, she is a douchebanger.
Grrrrr. I have to go visit my grandparents in Douchelandia over spring break. What a drag. Now all I have to look forward to is a week of stupid morons, douchebags and vapid twats. Great.