Moon day 

Usually used when you want to say you're on your period

A:Hey!
B:Don't talk to me I'm on my moon day

Moon day by Potterswifey December 10, 2021

sang moon day 

Usually a term used to describe the best day ever;
The term is usually used in professional golf tournaments

When a players posts an unbelievable round leading to a victory.
The term originated at the 2015 Barclays in Plainfield, New Jersey

Jordan Speith was having himself a sang moon day when he won the U.S Open.

sang moon day by Sang moon day October 14, 2015

International Yell At The Moon Day 

A holiday in which you can, without consequence, shout vulgarities at the moon.

International Yell At The Moon Day takes place on November 14th.

International Yell At The Moon Day by MaybeARealWord January 12, 2022

Moondays 

Something people occasionally get a case of on the first day of the modern work week. Add extra "oooo's" as necessary.

Office Worker #1: Good morning.
Office Worker #2: (No response)
Office Worker #3: Sounds like somebody has a case of the Moondays.

Moondays by Biff Masterson May 26, 2005

moonday

1. (n.), a day when a man cannot have sexual relations with his significant other for various reasons

2. (n.), saying "monday" with a weird accent

1. Jim's wife was going out of town on a business trip, and there would be many moondays before she returned.

2. Our term paper is due on moonday.

moonday by Kriptini June 20, 2010

Moonday

A Monday with a full moon.

Casey Berard posted a snapchat about Moonday on January 17, 2022, and now this is on Urban Dictionary.

Moonday by gbabyulm16 January 17, 2022

moonday

a day in which a blonde (or claire) considers to be a full moon.

ella: "I think i'll have a party moonday"
claire: "Is that when like there's a full moon or something?"
ella and rachel: "No stupid, moonday = MONDAY"

moonday by stoneleighite November 11, 2008