wag

set/start tongues wagging (informal)

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.

See also: set, start, tongue

the tail wagging the dog

if you describe a situation as the tail wagging the dog, you mean that the least important part of a situation has too much influence over the most important part. Steve thinks we should buy an orange carpet to match the lampshade but I think that would be a case of the tail wagging the dog.

See also: dog, tail