Now this is something you've got to see!

Dick Van Dyke celebrated his 90th birthday over the weekend by joining a Mary Poppins-themed flash mob to sing tunes from the hit movie!

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In the video, the actor can be seen singing and clapping as he watches a group dressed as chimney sweeps — just like his character Bert in the 1964 film — sing and dance to "Supercalifragilisticexpialidocious" and "Let's Go Fly a Kite!"

Watch the amazing video below.