Slapping, spanking, flogging, "golden showers," and the like are all forms of sadism. It's estimated that about 10% of the population has some sadistic/masochistic tendencies -- both homosexual and heterosexual. The S/M community, however, has some definite rules, the primary ones being safe, sane and consensual. What this man exhibited was none of those.

There are "wannabe" sadists, or dominants as they can be called, who have no idea what they are doing. They are dangerous because they can cause severe emotional and physical harm.

This woman should walk in the other direction. Quickly. Reporting him to the police would also be a consideration, particularly if he persists.

I forget who said it, but I don't get either that she invited him back!