Yes I Am!

Ever really look at the lyrics to Katy Perry's Hot N Cold?  Yes I am!

This part is especially applicable:
You change your mind
Like a girl changes clothes
Yeah you PMS
Like a bitch, I would know

And you overthink
Always speak cryptically
I should know
That you're no good for me

'Cause you're hot then you're cold
You're yes then you're no
You're in then you're out
You're up then you're down