be laughing out of the other side of (one's) mouth

be laughing out of the other side of (one's) mouth

To be experiencing a drastic change in one's emotions, often in a short span of time. A: "I thought your mother was happy that we're getting married." B: "Me too, but now she's laughing out of the other side of her mouth, and I get an angry phone call from her every day."

See also: laugh, mouth, of, other, out, side