Douglas Harper's Etymology Dictionary
boo-hoo
also boohoo, 1520s, originally of laughter or weeping (now only of weeping); see boo.
Usage examples of "boo-hoo".
Dawn Alice would be having a wonderful time in the role of distraught wife, shredding Kleenexes between bloody marys and boo-hooing on the tennis pro's shoulder while be fondled her buns and whispered obscenities in her ear.