Weirder Reality Changes?

You're suddenly confused, wondering why you have a phone in your hand. You hang it up, then turn your attention back to the calculator you received in the mail. It was counting down, you remember that clearly, but it didn't seem to do anything, not that you can figure, anyway.

At that moment, Kate walks into the kitchen. "Hey, bro, what's that?" she asks, pointing at the device.

You cringe a little, hearing her call you "bro". After all, you're Kate's sister. And Kate is your brother. Odd, something about that doesn't sound right. But everyone knows that sisters are male and brothers are female, right?