If it is you who slaps someone else you are expressing frustration of your desires. [1]
To dream that you slapped someone, suggests that you are harboring some deep anger and repressed rage. [2]
2. If slapped, one feels disrespected.
3. If the dreamer slaps someone, it indicates a disrespect toward that person or his/her ideas. [3]
If you got slapped, you will win some well-deserved but unexpected sodal kudos; if you observed, or did the slapping you are likely to suffer a social embarrassment. [4]