The 50% cotton/50% polyester Doctor Who Knock Knock T-Shirt is a blue shirt that is trying to be funny. Well... it is funny... not gonna lie, I laughed a little bit. Cause really now, who doesn't like a good Knock Knock joke? I sure do! Am I am sure you do too, which is why you plan on buying this shirt. You and I can both agree it is better than the whole, "orange you glad I didn't say banana" thing and I think you will solicit a plethora of glances from passersby. Some will get the joke, others won't but either way the Doctor Who Knock Knock T-Shirt will be a crowd pleaser.