Knock, knock, knock, "Penny?" Any fan of the hit sitcom "The Big Bang Theory" will instantly recognize Sheldon's trademark knocking pattern from his frequent visits to Penny's apartment. Order your t-shirt now, and start annoying your neighbors with your attire in addition to your Asperger's.

• Black or Red
• 100% Cotton
• Officially Licensed
• Standard Fit

More 'The Big Bang Theory' items: The Big Bang Theory Merchandise

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