Add “math” to the list of things you can’t do on an airplane lest you be mistaken for a terrorist. Ivy League economist Guido Menzio was pulled off an American Airlines flight and questioned after his seatmate pointed out he was too focused on writing in script she did not recognize, according to the Washington Post. It didn’t help that Menzio, who is Italian, has “dark, curly hair, olive skin and an exotic foreign accent.” Turns out the script was a differential equation. Menzio was working out “some properties of the model of price-setting he was about to present … on a working paper he co-authored about menu costs and price dispersion.” Last month a UC Berkeley researcher was removed from a flight after a passenger overheard him saying “inshallah” on his phone. We’ll be gathering signatures to petition for a minimum IQ for anyone who wants to be more than 10 feet off the ground, thanks.