OK, that guy is probably not a medical professional, but many pediatricians do in fact recommend using cocaine on children who have wounds. You see, cocaine has a couple of important properties that make it a valuable tool for treating lacerations. First, it is an effective local anesthetic. Once applied, it numbs the relevant area very quickly, typically in less than two minutes.
Secondly, cocaine is very effective at restricting bleeding, or even stopping it completely. It's a vasoconstrictor -- a drug that narrows blood vessels. The smaller a blood vessel gets, the less you bleed. As an additional benefit, once you've scoured your son's open wound with cocaine, not only will the pain be dulled and the bleeding stop, but he won't give a shit anymore.
"I feel fine now, we should just hang out and talk. Why don't we ever just talk? We should talk."
Of course, in a doctor's office, you won't see him or her dump an eight ball of coke on your kid's face. Doctors use a solution called TAC that is commonly used to treat bad cuts on the head, face or neck of kids, and it is 11 percent cocaine (roughly equal to a vial of Tony Montana's sweat). It's used because it is less painful and invasive than injecting a topical anesthetic and it doesn't distort or misshape the wound, which can increase the chance of scarring. No other drug combines the properties of a vasoconstrictor and an anesthetic. See, now when the cops show up to the accident, you can claim that those bags of coke are simply your first-aid kit.