[1975–80; whack(y) + -o]This word is first recorded in the period 1975–80. Other words that entered Englishat around the same time include: front-load, gridlock, hybridoma, methanogen, noogie-o is a suffix occurring as the final element in informal shortenings of nouns (ammo; combo; condo; limo; promo); -o also forms nouns, usually derogatory, for persons or things exemplifying or associatedwith that specified by the base noun or adjective (cheapo; pinko; sicko; weirdo; wino)