To frisk someone is to search them, usually for weapons. It’s typical for a crime show to portray a police officer frisking a suspect.
The purpose of frisking is to find out if someone is carrying a particular kind of item. The person doing the frisking may be looking for weapons or a recording device. Another meaning of frisk is more light-hearted: “to play in an enthusiastic manner.” Kids running around a playground are frisking. If you say there’s frisking going on in a nearby park, you might want to clarify which meaning you’re indicating.