Sannakji or sannakji hoe is a variety of hoe, or raw dish, in Korean cuisine. It consists of live nakji (hangul: 낙지, a small octopus) that has been cut into small pieces and served immediately, usually lightly seasoned with sesame and sesame oil. The nakji pieces are usually still squirming on the plate. It can also be served whole. (Wikipedia)
There is a real danger when eating sannakji which is that if a part is swallowed it could become a choking hazard because the suctions can stick to your throat. It is said that some Korean people have died from being too drunk to chew properly and choking on a part. I felt the suctions sticking to the roof of my mouth and it was pretty strong.