If the participants are actual teens, laughing and in control, the content is likely healthy. If the participants are adults playing teens, and the content is locked behind a paywall for fetishists, it is exploitative. And if the content depicts a minor—real or fictional—in a helpless, aroused, or pleading tickling scenario, it is likely illegal.
Participants should be able to stop the tickling at any time they feel uncomfortable.
: For many teens, tickling is an exploration of physical boundaries and sensory enjoyment.