: Slang for fellatio or oral sex, derived from the word isep (to suck). Contextual Usage
Alternatively, "Sepong" could be phonetic for "sponge," which in Indonesian is "busa." Maybe the phrase is about preparing something before using a sponge, but that seems odd. Alternatively, "sepong" could be a play on words with another term. Dedek Jilbab Kocokin Punya Ayang Sebelum Di Sepong