• It was a real slap in the face when he didn’t invite me to the wedding.
• The union leaders consider the 5% increase in the wages offered as a slap in the face.
• His remarks were a slap in the face for the local community.

Slap on the back – compliments, congratulations.

• The coach gave him a slap on the back for coming in first.
• Her boss gave her a slap on the back for completing the project before schedule.
• They deserve a hearty slap on the back for their efforts.