chemical burn
An insult so spectacular it transcends the realm of what would generally be classified as a burn and cuts deeper and more effectively into the self esteem of its object. The exclamation of "chemical burn!" is usually offered by a third party following a particularly vicious or clever dis, characterizing it as such. Chemical burns produce the metaphorical equivalent of extensive tissue damage.
IMHO, the dopest chemical burn in the movie The Love Guru is when Guru Pitka goes: "I like your hat. I used to have a hat like that once...then my mom got a job!"