The process of removing all Christmas decorations from your house, Christmas tree, etc. It is usually a long process, often done the day after Christmas.
"Hey Mike what are you doing on your ladder?"
"I'm dechristmasing the top of my house!"
An expression of dismay and anger, equivalent to damn emphasized by the Québécois swear word criss. May only be used as an interjection, as opposed to most swear words, which can be part of a sentence.