I don't know how to be mean?? Not kidding.?

So, all of my friends say I'm "too nice" and of course I don't want to change that FORVER but I want to prove to them that I can be mean ( I guess?) Like a lot of my friends will be like " Ew, Debbie is so gross she looks like a MAN!" and I'll just cover my face and be like " oh gosh" in the amazment that they said that. They say I do that all the time, hellllp? I'm in 8thhh grade btw. Thankkkks!