Not sure if a joke or not.

The dateline is the opening line of a news report, sometimes rendered in a different font like small caps, that states the location and date (though the date is often omitted, amusingly enough) of the described event. It's a very old meme that when reading a paper report for another medium the newscaster specifically declares when he's reading the dateline. It might have been used unironically back in the 1940s and 1950s, but I can only firsthand recall it being used in parody: The Muppet newscaster would occasionally do it, for instance. The US version of the game Rampage on the Commodore 64 did as well.