i've been offered, and have eaten, fugu (puffer fish) sashimi in japan. chef requires a special license due its toxicity, and is very pricey. my japanese hosts were delighted to order it on the company expense account with me as the excuse. that tingling sensation in the mouth is the purposeful low toxin dose to demonstrate the chef's prowess. i smiled and shared my remaining portion with my eager hosts. i figured that more sake was an antidote for whatever ails you.
if you ever ate smooth and/or inexpensive "scallops" you ate skate plugs.