Burnt Toast is an ill-omen given to human sacrifices. 
Once released on the weekend before St. Patrick's Day 1997, the Leprechaun went after descendants of those who imprisoned him in a Mystic Circle. He sent Mr. O'Toole burnt toast. O'Toole was ignorant of the implications but his housekeeper recognized it right away. Soon after, he was attacked by the Leprechaun and one of his Shillelagh Emanations. The Extreme Ghostbusters recovered the toast and took it to Egon Spengler for analysis. Kylie found an entry on burnt toast in Celtic Myth.