About three years ago, we adopted a stray cat. We already had two cats, but we welcomed this new one into out home. After we earned its trust (via food and warm beds), my dad assured the family that this was a female.
Fast forward to today. We finally get around to taking her to the vet. Since she still goes outside everyday, so we wanted to get her checked out and fully vaccinated. We go into the examination room, the nurse takes her back to draw her blood to test for feline leukemia, then bring her back, and the doctor comes in. We discuss various stuff, and mention that she must spayed; doc agrees, because otherwise, being outside would have gotten her pregnant already.
The doc goes in close, starts feeling around the stomach area, and looks at her rear. And tells us something vital:
"She" is a HE.
The doctor and the nurse give our newly male cat shots and de-worming pills, and we make another appointment for two booster shots. My mom and I leave the vet's, still in shock. My mom tells my dad when we get back, and I send a text message to my little brother at college (his response: "Lol wut?").
Moral of the story: when taking in a stray animal, see a vet as soon as possible. Or you'll go for three freaking years thinking it was one gender, when it was really another. We now have to get used to having one female cat, and two male cats.
By the way, we changed his name from "Misty" to just plain "Mist," to de-feminize him. Besides, we'd been calling him "Mist" as a nickname anyway, so this way we don't confuse the cat by completely changing his name.
Okay, you all may now commence hysterical laughter.