Bouncing Bob was riding a particularly frisky horse when suddenly its bridle came off. As they raced down the road, a screaming Bob clung to the horse's ears for dear life. Out of the corner of his eye, Bob saw a car coming, and realizing the horse was completely out of control, he panicked. Flailing his arms about, he accidentally caused the horse to come to an abrupt halt. What could Bouncing Bob have done to make the horse stop?