the time when a close friend, family member, significant other or associate retaliates on you because of an unsettled disagreement that you two have, usually in the form of outright rage, sneak disses, or the sharing of secrets. One person thinks the issue was resolved a while ago while the other person isn't over it. Mad day is very sudden and unexpected to the victim.
Example 1: Why are you putting all my shit out there? What is this, Mad day?

Example 2: Yo girl going the fuck check IG? She been posting subliminals all day ..she must've caught you huh bruh? It's Mad day!

Example 3:

You: I came outside to my car and breh my windows was busted out and my gas tank full of snicker bars....yo i don't get it ..we broke up like 3 months ago breh!

Yo Homie: Yeah man but last night was her MAD Day.
by Yodmbass June 8, 2017
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The one day a year everyone can just acts like a total Maddog, generally a mad dogging involves getting on the piss, speaking whats on your mind, getting on the bag, going to the rippas with a large circle of friends

On Maddog day you have to be super confident and not worry about any consequences, you act without control or worry for any of your actions.
"Oi champs, this year I'm declaring April 16th as Mad Dog day, for the entire day you get to act like a total Mad Dog. God Dam"

"Only Mad Dogs are April 16th Maddog day"
by PowderHounder April 12, 2018
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Similar to a "Bad Hair Day" although instead of having merely "bad" hair, your hair makes you resemble a mentally insane person.
"Oh my god! check Lloyd out, Mad Hair Day or what?!"

"Arhh, my hair just wouldn't work this morning, i'm having a total Mad Hair Day"
by KibbageBoy June 9, 2009
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A day of madness. Ever watch Alice in Wonderland? Well ayyyeeee that's what this day is. Yep, it's real. Google it. Grab a crazy ass hat 'cause this is gonna be mad.
Person1: What's with the hat??


Person1: The shit when did this exist
by RVPQueen March 17, 2016
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