How do you get people to pay attention to PSAs that try to teach people basic first aid? Many use shock tactics, but this ad, from the U.K.'s St John's Ambulance and BBH London, uses humor and animation to tell us how to save the life of a choking baby. The "characters" are four things that could potentially choke babies -- a small princess toy, a pen lid, a jelly baby and a peanut -- and they are voiced by celebrities David Walliams, David Mitchell, Johnny Vegas and Sir John Hurt (all of whom have distinctive voices that are well-known in the U.K..) They talk us through what to do, and then encourage us to share the film with friends and family.