From Wiktionary, the free dictionary
ông (“grandfather”) + nội (“paternal”)
ông nội
- a paternal grandfather
- Synonym: nội
- Coordinate term: bà nội
- (humorous, sarcastic) a sarcastic way of addressing a young boy or man who you're annoyed with
- Synonyms: bố, cha, nội, ông
Thôi dẹp đê ông nội !- Motherfucker, please!
Kêu ông nội đó về dùm tui với !- Would you escort His Highness home for me?