My parents owned a pet store, so I grew up in the animal business. And for some reason, the idea that "all calico cats are female" was the one thing that people would not, could not accept.
Every time somebody called in with a calico, we'd say "that must be female" and they'd go ballistic insisting NO IT'S NOT, IT'S MALE! Look, we've been over and over this, we'd say. NO, I SWEAR TO GOD, I HAVE A MALE CALICO, IT'S BUTCH, IT'S SPITTING TOBACCO JUICE RIGHT NOW!!! Alright, alright, bring it in! If it's a calico male, it'll be worth the time and trouble because we'd love to be on the front page of the New York Times tomorrow, to say nothing of the Guinness Book of World Records next year.
They bring it in.
Yep, female. Invariably, they'd all respond this way: "Doooooooh! I didn't know that! So that explains why he kept having litters of kittens!" ARGH!
The other case is where they have a male, but it's not calico. OK, in order for a cat to be considered "calico", it must have all three of the colors white, black, and orange, in a spotted pattern. This is a calico...
The only other variation allowed to be called "calico" is the "tortoiseshell" pattern, which has the black and orange but little or no white. This is a tortoiseshell...
That's it - if your cat does not resemble either of these, it's not a calico. This is not a calico...
People keep insisting that male calico cats can exist. No, they can't. Even though this fallacy has found its way into the literature, so that it reads like "99.9999% of calico cats are female, but you just might have a male calico so be sure to argue about it". Those reports of male calicos all come from people who (a) don't know how to tell a cat's sex, or (b) don't know what a calico cat looks like.
I blame Evangelical Christians. Their reasoning goes "I see a calico cat, so there must have been a breeding pair of calico cats on Noah's Ark, therefore male calicos must exist."
Calico and tortoiseshell cats are always female because there's a link between color pattern and the X chromosome. The gene for being white with orange spots is on the X chromosome. And the pattern for white and black spots is also on the X chromosome. There is no gene in cats for white with orange and black spots, total. So the only way to get both color patterns overlapping is for it to have two X chromosomes! It is possible for genetic freaks to be born with an XXY chromosome, regardless of color, but these are not true males - they're even sterile.