Kamyeonsosu

Kamyeonsosu (가면소수, 假面所崇), or FAKE MASK, is a peculiar, spirited object with quite peculiar effects on humans. 

Its appearance is identical to mushrooms, and if you are unlucky enough, you could find it in Korean forests. This is probably the reason why the second part of its name uses the hanja 所崇 (소수), meaning "in the mountains".  

This magical and spirited mushroom appears for the first time in the Collection of Stories compiled in 1512 by Lee Yuk's (李陸, 1438~1498) under the name: Cheongpa (청파극담).

TOUCHING it might cause illnesses and distress;

EATING it will give euphoric feelings, extreme happiness, which might lead you to...

KEEP EATING it, and at this stage the unlucky human will dance and sing without control over its body.