Literally, one who is experienced in excelling, especially in situations concerning catastrophes. However, this term is often used sarcastically, when the person described has actually performed a negatively noteworthy action.
Tiffany: "So Thomas Jefferson had a prostitute he took around in a carriage."
Stephen: "Beast master of disaster..."
Tiffany: "What did you say???"
Justin: "Dieu, mistakes were made."
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