If the calendar was written in C++ or many of it’s derivatives then signed integer overflow is undefined behaviour and it could technically choose to do anything it damn well wants (unsigned integers actually do have defined overflow behaviour). Something tells me the runtime of a paper calendar is anything but standard :D
Are we still calling it Y2k38? I think it needs some rebranding or we won’t be able recruit devs to put in the overtime to fix it so history can decide it was all fake.