The phrase "kick in the teeth" is often used to describe a harsh and unexpected blow or setback. However, there are several synonyms one can use to convey a similar idea. One option is "slap in the face," which suggests a humiliating and insulting attack. Another synonym is "punch in the gut," which connotes a sudden and painful blow to one's emotional or physical well-being. "Rude awakening" is another apt synonym, describing a jarring and unpleasant shock that wakes one up from complacency. Finally, "bitter pill to swallow" suggests a difficult or unpleasant truth that is hard to accept.