As Mr Jaitley was expounding on the bullet train initiative of the Narendra Modi government and rued that most debates on the issue he came across in India were "ill-informed", a man in the audience stood up.
He said: "Arun-ji, bullet train ko Hindi mein kya kehte hain? Hindi mein angrezi mat batiyaiye (What is a bullet train called in Hindi? Don't use English words while speaking in Hindi)."
Mr Jaitley, visibly annoyed, then told him to be a "little serious".
"Be a little serious please. You have been noticed once, thoda serious hone ka... gambhir hone ka bhi prayas kijiye (try to be serious)."
The man, however, persisted he had raised a "very serious" issue.
On September 14, Prime Minister Narendra Modi and his Japanese counterpart Shinzo Abe laid in Ahmadabad in Gujarat the foundation stone of the country's first 508-km high-speed bullet train between Mumbai and Ahmedabad.