kick in the pants

kick in the pants или kick in the teeth  {n. phr.},  {informal}

Неожиданная насмешка или оскорбление тогда как ожидалась похвала; непринятие.

Mary worked hard to clean up John's room, but all she got for her trouble was a kick in the teeth.

Ср.: SLAP IN THE FACE.