Act innocent, cute, or extra polite. Start to cry. This one is a departure for the mature salesperson, but don't discount its power. If you think this list is far-fetched, consider the closing rate of children. Now look at your closing rate.
Some kid stuff has a reverse effect.
Overzealous closing tactics like foot stomping, wall hitting, door slamming, stuff kicking, and the tried and true fit throwing, usually get the punishment rather than the prize. They have an understanding for people, and play on their weaknesses. Persistence is the biggest lesson I've learned from kids. Kids are having fun. And kids take risks.