<P> In Poland , prima aprilis ( `` 1 April '' in Latin ) as a day of jokes is a centuries - long tradition . It is a day in which many jokes are told ; various hoaxes -- sometimes very sophisticated -- are prepared by people , media ( which often cooperate to make the `` information '' more credible ) and even public institutions . Serious activities are usually avoided , and generally every word said on April 1st can be a lie , or a joke . The conviction for this is so strong that the Polish anti-Turkish alliance with Leopold I signed on April 1 , 1683 , was backdated to March 31 . However , for some in Poland prima aprilis ends at noon of April 1st , and prima aprilis jokes after that hour are considered inappropriate and not classy . </P>
when does april fools day end at noon
April 1st