kick in the teeth idiom informal
（尤指在需要帮助时遭受的）恶劣待遇，严重打击
If you describe the way someone treats you as a kick in the teeth, you mean that that person treats you badly and unfairly, especially at a time when you need their support.
She was dismissed from her job, which was a real kick in the teeth after all the work she'd done. 她辛辛苦苦做了那么多工作之后被解雇了，这使她深受打击。