be all mouth and no trousers
US /bi ɔl maʊθ ænd noʊ ˈtraʊzərz/
UK /bi ɔl maʊθ ænd noʊ ˈtraʊzərz/
1.
to talk a lot about what you are going to do but fail to actually do it
:
•
He's always boasting about his plans, but he's all mouth and no trousers.
•
Don't listen to her promises; she's all mouth and no trousers.