Let your hair down = to relaxI �m tearing my hair out = I �m frustrated/angry/anxious
Keep an eye on something = to monitor something closely
To have eyes in the back of your head = to seem to be able to sense what is going on behind or outside of your field of vision. My teacher seems to have eyes in the back of her head.
His eyes are bigger than his stomach - he piled more than his fill onto the plate and is now unable to eat it; he has taken more food than he can eat
I �m pulling your leg = I �m kidding you; I �m joking
It cost me an arm and a leg = it was very expensive
You haven �t got a leg to stand on = to be in a situation where you cannot prove something
