90-Year-Old Dick Van Dyke Joins Flash Mob and Sings (VIDEO)

December 12th was a big day...it was the day Dick Van Dyke joined a flash mob for his 90th birthday!

Dick Van Dyke dances every day. If you follow him on Vine, you'll see a ton of videos of DVD dancing. At Costco, in the park. Anywhere he feels the beat, he dances. Nothing big and fancy, but you can tell he's got the go go go in him.

In his new book (Keep Moving) he says he has the old-age problems like everyone else, but if he has a secret to being so spry, it's that he refuses to go down the stairs sideways or backwards. It hurts to go forward, but he's afraid if he goes any other way, he'll take the safe way for the rest of his life.

Anyway...December 12th, he kicked off his 90th birthday aqt The Grove in Los Angeles. His wife arranged a flash mob doing Mary Poppins songs. And he joined in!  Now that's moving!