고 미치다

be driven crazy by it

미치다 is going out of your mind, and 미치겠다 in speech is 'this is driving me mad' — something that won't come out, someone who won't listen to a word. It flips into praise just as easily: 먹고 미치는 줄 알았어 is 'it was so good I nearly lost it'. 미친 듯이 is 'like a maniac', which one caption uses of someone sprinting.

Register: very casual, emphatic