"Keep your Lawn Darts at home?" Why does that seller hate fun?
Lawn Darts are completely awesome, and only if you're a total moron would you be in any danger of hurting yourself, or putting other people in danger. If you use them improperly or are an idiot, then yes, you can be in a bad way in a damn hurry.
Along with a sealed copy of Ticket to Ride for eight bucks, a set of lawn darts might be my best thrift/rummage sale purchase.