My Dad just asked me why there isn't a Day for Men. So I told him about the time when Alice met Humpty Dumpty.
Since I cannot put it better than Lewis Carroll himself, I shall copy-paste the relevant bit for those who haven't read Through the Looking Glass and What Alice Found There.
"What a beautiful belt you've got on!" Alice suddenly remarked. (They had had quite enough of the subject of age, she thought: and if they were really to take turns in choosing subjects, it was her turn now). "At least," she corrected herself on second thoughts, "a beautiful cravat, I should have said -- no, a belt, I mean -- oh, I beg your pardon!" she added in dismay, for Humpty Dumpty looked thoroughly offended, and she began to wish she hadn't chosen that subject. "If only I knew," she thought to herself, "which was neck and which was waist!"
Evidently Humpty Dumpty was very angry, though he said nothing for a minute or two. When he did speak again, it was in a deep growl.
"It is a -- most -- provoking -- thing," he said at last, "when a person doesn't know a cravat from a belt!"
"I know it's very ignorant of me," Alice replied in so humble a tone that Humpty Dumpty relented.
"It's a cravat, child, and a beautiful one, as you say. It's a present from the White King and Queen. There now!"
"Is it really?" said Alice, quite pleased to find she had chosen a good subject, after all.
"They gave it me," Humpty Dumpty continued thoughtfully, as he crossed one knee over the other and clasped his hands round it, " -- for an un-birthday present."
"I beg your pardon?" Alice said with a puzzled air.
"I'm not offended," said Humpty Dumpty.
"I mean, what is an un-birthday present?"
"A present given when it isn't your birthday, of course.
Alice considered a little. "I like birthday presents best," she said at last.
"You don't know what you're talking about!" cried Humpty Dumpty. "How many days are there in a year?"
"Three hundred and sixty-five," said Alice.
"And how many birthdays have you?"
"And if you take one from three hundred and sixty-five, what remains?"
"Three hundred and sixty-four, of course."
Humpty Dumpty looked doubtfuly. "I'd rather see that done on paper," he said.
Alice couldn't help smiling as she took out her memorandum-book, and worked the sum for him:
Humpty Dumpty took the book, and looked at it very carefully. "That seems to be done right -- -" he began.
"You're holding it upside down!" Alice interrupted.
"To be sure I was!" Humpty Dumpty said gaily, as she turned it round for him. "I thought it looked a little queer. As I was saying, that seems to be done right -- though I haven't time to look it over thoroughly just now -- and that shows that there are three hundred and sixty-four days when you get un-birthday presents -- -"
"Certainly," said Alice.
"And only one for birthday presents, you know, There's glory for you!"
As I gently explained to my Father Un-birthdays and Men's Days are rather similar, given they're celebrated on every day that Birthdays and Woman's Days aren't. There's glory for you indeed.