A triple-threat portmanteau combining the words Thick, Thong, and Showing (or Going). It specifically describes the visual
phenomenon where a woman’s buttocks are large enough to completely "swallow" or obscure the thong she is wearing.
Instead of the full waistband being visible, the fabric is hidden by her "thickness," leaving only a small portion—like the top of the "T" or the back triangle—peering out.
The term also plays on the slang "Going" or "Goer," referring to a woman who is high-energy and
sexually active. When a girl is "thoing," the garment is
practically invisible or "gone" due to her size, signaling she is a "goer" who is "showing" just enough to be a teaser.