when you hit someone with the palm of your hand, usually to the face
ow fucker why did you slap me like that
When music is really good
This track slaps the rubber pants off the lab rats!
to hit someone (or something) with the palm of his/her hand on the targeted part of the body (or object).
fuck nigga gets bitch slapped.
When a food item is better than expected/the best ever.
Yo, your grandmas mac'n'cheese slaps.