flip one's lid
1. To lose one's temper.
When that pushy salesman came back Mom really flipped her lid.
Compare: BLOW A FUSE.
2. To lose your mind; become insane.
When he offered me three times the pay I was getting, I thought he had flipped his lid.
3. To become unreasonably enthusiastic.
She flipped her lid over a hat she saw in the store window.
He's flipped his lid over that new actress.