screw
have a screw loose be slightly eccentric or mentally disturbed. informal
put the screws on exert strong psychological pressure on someone so as to intimidate them into doing something. informal
screw up your courage summon up all your courage; force yourself to be brave.
tighten (or turn) the screw (or screws) exert strong pressure on someone. informal
a (final or last) turn of the screw an additional amount of pressure or hardship applied to a situation that is already extremely difficult to bear. informal