A quote from Princess Leia to Han Solo in Star Wars Episode V: The Empire Strikes Back.
Well lemme break it down.
Chilly sounds exactly like chili. CHILI is a type of spicy chowder that people enjoy with a side of bread or crackers. CHILLY is a state of weather. It is usually associated with cool temperatures. Therefore, because your mother was mentally unprepared to handle such a phrase, she mixed up the two and decided to go for the 'chili' that she believed was awaiting her outside. See also Chili, So Dumb, Yo Mama.