Calculus shirts are shirts that contain references to calculus, usually in the form of a pun or a joke. These shirts often draw upon different functions and properties in the study of calculus and connect them to real-life emotions or events.
On Zazzle.com, a website where anyone can purchase T-shirts, one of these calculus shirts includes the joke, "calculus and alcohol don't mix; don't drink and derive." Other shirts include equations that hint at certain puns and jokes about how calculus is the cause of sleep-deprivation.
These calculus shirts can be bought from several websites online. Another site where they are available is Spreadshirt.com, which allows you to either buy a pre-made shirt or print a calculus joke on a custom-made shirt.