Then you're probably using it incorrectly, and did more harm than good. NEVER do CPR on ANYONE without a physical obstruction, unless they've been unconcious for more than 30 seconds without breathing restoring naturally, or you witnessed them have a heart attack. Doing CPR on someone who was "choking" on a blunt is flat uncalled for. They'll cough like hell. They might throw up. They'll be fine. Never do that again. You could end up with a lawsuit for broken ribs, if you're doing it correctly, and a wrongful death suit, if you do it wrong.