Dic: set/start tongues wagging, cause (some) tongues to wag

if something that someone says or does sets tongues wagging, it causes people to talk about them.

• His late-night visit to her home has set tongues wagging. 
• The way John was looking at Mary will surely cause some tongues to wag. The way Mary was so scantily dressed will also cause tongues to wag.

.... http://idioms.thefreedictionary.com/wag