Why have I been acting out lately?

I'm a 15 year old guy and I get really good grades and never talk in class then this semester I met a girl and I like her, all of a sudden I haven't been acting myself I've been doing dumb things to try and impress her I'm even getting kicked out of class for interruptions and talking back, which is very unlike me, but she seems to get a kick out of my different side, why is this happening I never behave in such a bad manor