Russell Westbrook doesn't want your penis to suffocate ... and that's why the Oklahoma City Thunder star just signed a deal to model a high end underwear line that prides itself on "wiggle room," TMZ Sports has learned.
Our well-placed underwear sources tell us ... Russell inked a huge deal with Kings and Jaxs that will require him to not only model the undies, but will also give him creative and design input.
FYI --K&J prides itself on how the underwear is built to let your man parts breath -- the web site says, "The little man doesn't like to be restricted with little or no oxygen."
As for Russell, he's already posed for several pics in the undies -- some without a shirt -- and dude's jacked.
Of course, Russell ain't the first NBA star to hawk un-man-tionables -- Dwight Howard has modeled undies for Adidas ... and of course, Michael Jordan is the face of Hanes.