I haven't ever heard of this ever actually happening, though because of the nausea-inducing compounds(Cyanogenic glycosides) this can potentially occur. Keep in mind, though, that those same compounds naturally occur in peach cores and apple seeds,
It seems I may have had one, though. I ingested 12 pills with some Gatorade on an empty stomach, and then smoked a bit of green to curb the nausea because I really didn't feel up for vomiting at the time..
within 30 minutes though, I just began to feel the effects and promptly passed out completely randomly afterwards. I woke up in an emergency room with a tube down my throat because I'd stopped breathing, apparently. Other than that I was perfectly fine, and felt and performed completely normally upon waking up, aside from some damage caused by the ambulance's rough work.
This has always bothered me, does this mean there is a potential of lethal side effects from HBW seeds?