I'm Married to the Most Wonderful Woman in the Galaxy Day
I'm Married to the Most Wonderful Woman in the Galaxy Day was a "holiday" invented by Miles O'Brien in 2371. According to him, it was an old Irish tradition.

After the school on Deep Space 9 closed down as a result of the evacuation of Bajoran families due to the impending conflict, Keiko O'Brien was feeling depressed. To cheer her up, Miles told her about the holiday and claimed to have marked it on her calendar. 

According to Miles, it was an irregular holiday that occurred unpredictably, sometimes twice a day. When Keiko asked what kinds of things usually accompanied the holiday, giving cake, noisemakers and fireworks as examples, Miles assured her, "Definitely fireworks." ()
Celebrations
Earth
Fictional