This, n I don't practice jui jitsu, but when your hand eye coordination needs to be dead on to avoid gettin hurt, doing any drugs is a bad idea.
actually, Nick Diaz, Eddie Bravo & Joe Rogan are known smokers & BBJ practioners, amongst many others. There are videos of Eddie Bravo smoking weed then going and training. You're not going to get your arm broken because you got high beforehand. I don't do BJJ either but I really want to get into it.