Ohhh .... The Duct Tape!
I've used it sooo many times. I can make a longest post here, FULL of duct tape

, but I'll just mention couple of things I've done.
Ever played Cricket? For those who never did, cricket bat is made out of two parts, and both parts are joined together with very strong glue. So once it came apart and i used duct tape to fix it and played a professional match with it. Also I've used duct tape several times to temp fix the punctures in a football (also known as soccer ball). Other than that, i made a grip for my tennis and badminton racket/racquet out of duct tape. Like other have mentioned before i also own a duct tape wallet. Once i found a lead (fallen out of a pencil) so i made a Duct Tape Pencil out of that

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