Off the Record:
Something said in confidence that the one speaking
doesn't want attributed to him/her.
On Pins And Needles:
Anxious or nervous, especially in anticipation of
something.
On The Fence:
Undecided.
On The Same Page:
When multiple people all agree on the same thing.
Out Of The Blue:
Something that suddenly and unexpectedly occurs.
Over My Dead Body:
When you absolutely will not allow something to happen.
Over the Top:
Very excessive.