Why not? He or she will learn that at any given moment very few people are ready for a slap and can be easily overwhelmed.I'd hate to see someone read this thread and go trying to slap someone.
To effectively slap someone all you need is a reason (ie, a vague answer to a question) and strong and pointed dialogue to accompany ("I asked you where I could rent a canoe, not about your fears of camping!") and you'll be fine.