Learning any language is tough. English is no exception. But if you're a big company producing T-shirts to sell, and the T-shirts have sayings in English, don't you think you should pay someone like me a dollar to check and fix T-shirts like the one I saw in Brno which said,
"Expect for the best. Be prepare for the worst."
Nice motto, but...not so nice grammar.
Then, on a nicely printed color map of a Czech folk festival, they translated "šatna" creatively. I would translate "šatna" as "dressing room" or "changing area" or something, but they translated it as "hinterland." So, the end result was "Hinterland for Performers." Banish those performers to the inland wilderness away from all centers of civilization! :) I got a kick out of it. But...I'm not sure the organizers were really intending to make English speakers laugh.