freak-out (n.)

also freakout "bad psychedelic drug trip," or something comparable to one, 1966, from verbal phrase freak out, attested from 1965 in the drug sense (from 1902 in a sense "change, distort, come out of alignment"); see freak (n.). There is a coincidental appearance of the phrase in "Fanny Hill:"

She had had her freak out, and had pretty plentifully drowned her curiosity in a glut of pleasure .... [Cleland, "Memoirs of a Woman of Pleasure," 1749]

where the sense is "she had concluded her prank."