Look it's a knock-off Cheers! shirt. It's close enough to the original design that some of your friends will start singing the old tv show's theme song, but surprise! It's not like that at all. It's a knock-off!
But hey, it's an age-old salutation to raise a glass to, and wish others good luck and good cheer with. Across cultures and countries we've distilled the well-wishes of inebriated strangers into a single, boisterous word. So put it on your chest and let the good times roll.