Set tongues wagging
Definition 1 of 1
Pro Tip 1/3Gossip Trigger
Use this phrase when an event or action sparks curiosity and leads to people talking a lot. 
Their secret wedding set tongues wagging across the small town.
Pro Tip 2/3Caution with Seriousness
Avoid using it for extremely serious or sensitive topics where gossip would seem inappropriate. 
The phrase wouldn't fit in a discussion about a funeral that set tongues wagging.
Pro Tip 3/3Informal Context
It's commonly used in informal situations and might not suit formal writings or speeches. 
She changed her hair color and it set tongues wagging at the reunion.