Looking every inch a loser, “American Idol” winner DAVID COOK refused to close dressing room drapes while trying on jeans at a high-end Hollywood boutique – casually exposing what Dude apparently thinks is a sex-god bod, clad in nuthin’ but tighty-whities!

When a salesgirl went to close the curtains so he could undress “in private” (hint, hint!), Cook actually refused, saying he doesn’t like being, like…uh…“closed in.”

One turned-off shopper shouted “GEEK!” as Cook continued his undie-niably lame striptease, slipping in and out of jeans and shirts like he was home alone as gob-smacked patrons made barf-signs.

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