When can I start swearing? (Not a troll, true story?!?!?

I want to swear so bad I never swore in my life, well maybe in my mind I do swear, but not when I talk. I'm 11 years old and Kids younger than me (9 year olds) and maybe young teenagers are starting to swear in my area. A girl who is my age swears alot and I want to be cool like her but just because I'm such a crybaby I always cry and those kind of kids tease me about it cause I can't say it into their faces or swear to them. When can I start swearing? I want to be cool like them too!