Kick In The Teeth Meaning

(idiomatic) A humiliating insult or instance of bad treatment, especially when one is expecting friendship or in need of support; a sudden and unexpected setback; a strong rebuff.

Example: 1996, Evelyn Shakir, Arab-American Literature, in Alpana Sharma Knippling (editor), New Immigrant Literatures in the United States: A Sourcebook to Our Multicultural Literary Heritage, page 13,
  This kick in the teeth, brutal under any circumstances, is more so, given Matoussem Ramoud's gentle, trusting nature and his infatuation with America.
1998, Annetta Louise Gomez-Jefferson, In Darkness with God: The Life of Joseph Gomez, a Bishop in the African Methodist Episcopal Church, page 331,
  King had remarked after the bill failed that a lot of people had lost faith in America; Roy Wilkins had said, “This defeat was a kick in the teeth to the civil rights effort.”
2006, Kevin Leman, Sex Begins in the Kitchen: Creating Intimacy to Make Your Marriage Sizzle, page 119,
  She had found her niche by being truant from school, giving people a bad time, and basically giving her parents' strict moral values a good, strong kick in the teeth.