T.H.O Share definition Flag Titty Hard On the act of ones nipples contracting and getting "hard" Maggie was embarassed because all her class mates could see her T.H.O through her shirt. T.H.O by nobodythatuneedtobeconcernedwith May 18, 2003 0 0 Get merch Get the T.H.O mug. Buy Now — $32.95 See more merch