hop-tu-naa is a continuation of the manx "oie houiney", which is exactly the same as the irish "oíche shamhna" and which was pronounced the same (though not in revived manx). the exact status of oíche shamhna and its role in the celtic calendar has been a matter of debate. oíche shamhna eventually mutated into halloween in northern england and in ireland, it was carried to america by irish immigrants and developed into the modern halloween.