Like a wenis, except on your knee instead of your elbow (i.e. the stretchy skin on your knee).
John: "Whoa my knenis is so big!"
Dave: "Uhh...dude why would you tell me that?"
John: "Haha, no I said KNENIS, get your mind out of the gutter!"
by Benjy Benjerson February 12, 2009
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