And that's not all! From now until midnight PST, you can take $10 off your order of $60 or more and $15 off your order of $75 or more in the mental_floss store! Just use the codes SAVEME10 or SAVEME15 at checkout. (Offer excludes clearance, subscriptions, and package deals.)
Did you know that you can submit t-shirt slogans? Cyrus L. Jr. of Birmingham, Alabama came up with Pi Hard, and Renier Fee of Brooklyn, New York sent us the idea for McPi. They get $125, a free shirt, and eternal "I designed a mental_floss t-shirt!" bragging rights. If you have a funny t-shirt slogan, you can submit it here.