What do i do if my sister is being super annoying and i just want to slap her across the face?

There's a little something called patience. It's really good. And there's also forgiveness. You should try both

same story as u.

I usually imagine it.

Try ignoring her, that might make it seem like you don't really care.

instead of wanting to slap your sister take your agression out on your pillow,or one of those clown blowup dolls or a punching bag

First you need to calm down and ignore her. Tell her to stop being annoying if you can. Don't resort to hitting her to stop her from being annoying. You'll get in trouble and she'll probably not like you anymore.

Slap her or ignore.
My bro is the same.

Slap her. Suffer the consequences.