In general: to leave behind one's inhibitions or to behave in a way that is free from social limitations or any code of conduct
Let your hair down and tell me all about yourself. Come on. Let your hair down and tell me what you really think.
by Harald Fairhair January 5, 2012
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going overboard with effort or giving more effort than is required for a simple task
wow you really let your hair down today at noon ball, i think you actually killed a guy
by andydalton January 17, 2012
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