change (your) tune

to change your opinion completely, especially because you know it will bring you an advantage.

He was against the idea to start with, but he soon changed his tune when I told him how much money he'd get out of it.

• fall into your lap
• fall off
• fall off perch
• fall off the map
• fall off the wagon
• fall off your perch
• fall on deaf ears
• fall on hard times
• fall on stony ground
• fall out with
• fall out with someone
• fall over
• fall over yourself to do something
• fall prey to
• fall prey to someone
• fall prey to something
• fall short
• fall short of
• fall short of something
• falls on deaf ears
• fall through
• fall through the cracks
• fall through the floor
• fall to pieces
• false alarm