How to deal w/ a brat sister?

I hav a 14 yr. old sister n she's been drivin me nuts! i mean like if things don't go her way she keeps complaining n blaming on me, like just yesterday i wanted to juz chill out at home ya know n chat on internet w/ my buds who are visitin their relatives out of state, but when i say i can't go play outside w/ her juz for today she then juz starts her tantrum starts cussing phrases that she heard from her friends...the thing is im bout to go nuts! i would usually juz hang w/ my buds but since they're all out of town w/ aunts n uncles so i've already like played tennis w/ her outside for past 2 weeks! yesterday i told her to go play w/ her friends who are like only a block away n are at home, then she juz makes n excuse that they're probably too busy n wouldn't even go ring the door bell even tho i said i would go w/ her, i know 2 weeks may seem short but the way she won't give me at least one day to juz chill she complains!