I was taught "point at someone and tell them 'you, specifically, call 911'" but I like touch a lot better. Makes more sense for getting someone to actually do it.
replyTouching someone when asking them to do something is a well known psychological trick. It immediately increases intimacy, which makes the person more likely to do what you ask. Though it can also backfire if the person is particularly sensitive and finds the intimacy uncomfortable.
replyI had this directive as well.
replyI was told to point at someone and say, "YOU. Call 911."