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Underpants normally worn by men of the homosexual persuasion, whereby the opening pouch is located at the rear as opposed to the front.
I'm going out speed fudging tonight, so I got me Y Backs on for easy access!
by Dickie Brooks September 21, 2007
Tank top worn by bodybuilders that has two straps in the front and comes together in the back as one strap making a Y appearance.
Travis has a sweet y-back, but Tyler definently fills it out better because he is more huge.
by tommytoughnuts April 23, 2008