Thermos flask for hot and cold drinks

Did you hear about the man who brought a flask to work with his tiffin case?
His workmates ask: "What's that?"
He says: "It's a thermos flask. It keeps hot drinks hot and cold drinks cold."
Amazed, the man ask (sic): What's inside?"
He replies: "Two cups of hot milk tea and a fizzy cola."

cf. tiffin: a small meal that you eat in the middle of the day
sic: used in writing after a word that is not spelled or used correctly to show that you have written it that way because you are repeating what someone else said or wrote