Halloween is oíche shamhna, Samhain night, New Year's Eve. In that time between the end of the last day of the old year and the first light of the new ghosts may walk, the púca rides the countryside and anything may be abroad!
The púca, or pooka, is said to blight all fruits not harvested by tomorrow morning, making them unedible (you probably don't want to know how he does this, as it involves bodily fluids). But then, all the harvest should be in by now--turf gathered, crops under cover, livestock secured. Winter begins with November 1, after all! And winter starts with a feast...I prefer chocolate, myself!
Oh, and please...if I ask one thing it's that you pronounce it right. The word Samhain is 'SOW-uhn' (rhymes with cow), and NOT 'SAM HAIN'! In Irish 'amha' is 'ow'. Samhain is also the modern name for the month of November, so there's your Irish word of the month.