Here's this piece culled from NY Times:

A couple of months ago, it was a color-changing dress that blew out the neural circuits of the Internet . Though it may not have quite the mass appeal, this week it is a math problem that is making bushels of brains hurt. It started with a posting on Facebook,
by Kenneth Kong, a television host in Singapore.
From there, people around the world have been trying to figure out Cheryl’s birthday, or at least wondering why she couldn’t she just save everyone a lot of trouble and be more direct with Albert and Bernard?
The wording of the problem is terrible, so here is a clearer version, which makes some of the assumptions more obvious but which does not
change any of the underlying logic of
the problem:
Albert and Bernard just met Cheryl. “When’s your birthday?” Albert asked Cheryl. Cheryl thought a second and said, “I’m not going to tell you, but I’ll give you some clues.” She wrote down a list of 10 dates:
May 15 — May 16 — May 19
June 17 — June 18
July 14 — July 16
August 14 — August 15 — August 17
“My birthday is one of these,” she said.
Then Cheryl whispered in Albert’s ear the month — and only the month — of her birthday. To Bernard, she whispered the day, and only the day.
“Can you figure it out now?” she asked Albert.
Albert: I don’t know when your birthday is, but I know Bernard doesn’t know, either.
Bernard: I didn’t know originally, but now I do.
Albert: Well, now I know, too!
When is Cheryl’s birthday?


Do YOU know?

Answer's in a bit.

Meanwhile...

July 16