Whereas its partner word, ack, is transparent (if not utter genius) in its meaning, thppt is shrouded in mystery. Was Bill spitting? Did he need a drink of water?
Opus the Penguin would also ejaculate this strange conglomerate of consonants from time to time. It is in the consistency of his expression that we may have a clue as to its meaning: a squint-eyed scrunching of the nose with puckered mouth, often accompanied by protruding tongue. It conveys distaste and disapproval.
As with Bill, however, I am left to wonder: what does Opus really feel?