The story
Onomatopoeic, imitative of a full spitting sound. The catchphrase went viral after a street interview conducted in June 2024 with Haliey Welch, who stated that her signature move for making a man “go crazy” in bed was to “give him that hawk tuah and spit on that thang”. However, isolated uses exist earlier (albeit without the association with oral sex). Perhaps compare ptui (“spitting sound”).
Etymology from Wiktionary, CC BY-SA 4.0.