Both Korean and Khmer have unreleased final stops (p, t, k without a puff of air). Most European languages do not have this. When Vincenzo says "Muk" (먹 - "eat"), his lips close without explosion. This is identical to the Khmer word "Muk" (មុខ - "face").
Multiply these similarities by a hundred lines of dialogue, and you have a recipe for a bilingual hallucination.
A more sophisticated version of the "Vincenzo Speak Khmer" theory arises from the show’s legal themes. Cambodia has a unique legal system influenced by French civil law and traditional customs—radically different from the Italian and Korean systems Vincenzo navigates. Vincenzo Speak Khmer
Some fan-fiction writers have proposed an alternate backstory: What if Vincenzo hid out in Phnom Penh during one of his clan wars? In this headcanon, Vincenzo learned survival Khmer to negotiate with arms dealers along the Mekong.
While this makes for a thrilling fan edit, there is zero canonical evidence. The writers of Vincenzo (Park Jae-bum and Kim Young-woon) never included Khmer dialogue in the script. The languages used are strictly Korean, English, Italian, German (briefly), and Chinese. Both Korean and Khmer have unreleased final stops
Let’s be honest—Khmer has some sounds that don’t exist in Korean or Italian. The infamous “រ” (ro) and the vowel clusters would trip up anyone. But Vincenzo? He’d master it in a week.
Why? Because the man is canonically a perfectionist. He learned Korean to win a legal battle. He’d learn Khmer just to out-argue a Cambodian money launderer. A more sophisticated version of the "Vincenzo Speak
Fan theory: Vincenzo spent three months in Phnom Penh during his “gap year” of crime. He doesn’t talk about it. But when a Khmer-speaking witness shows up in episode 15, Vincenzo just tilts his head and says:
“អ្នកនិយាយយឺតពេក” (Neak niyeay yuert pek.) “You speak too slowly.”
Cut to Cha-young’s shocked face. Cut to the witness sweating. Iconic.