口蜜腹剑
[词典] play a double game; a cruel heart under the cover of sugar-coated words; A honey tongue, a heart of gall.; A man may smile and smile and be a villain.; a Judas kiss;
[例句]从他们这些年的所作所为看来，他们的确是口蜜腹剑的“朋友”。
Judging from what they have done these years, they are indeed “ friends ” with an honey tongue and a heart of gall.