Has anyone here done improv/comedy?

Has anyone here done improv/comedy? I really want to try it out. I know it'll be a huge huge challenge for me and a mentally stressful event. I've done debates and formal stuff before so I don't have alot of stage fright. However stuttering and people responding negatively does scare me quite a bit. My stutter is the blocking kind where I block on certain words or run out of breath basically. Has anyone done any sort of improv or comedy before? What was it like and what's re your tips/reccomendations?