Michael has been doing elaborate fallings-over for some time now. He has a good look behind for any difficult obstacles, then topples backwards gently with arms windmilling. He can fill hours with this. Sometimes it is silent and sometimes accompanied by "Whoa, whoooa, whooooooa!"
I think it was originally inspired by Captain Feathersword of The Wiggles, who also does a lot of falling over with elaborate flailing of the arms. Now Michael has taken it to a new level. Marcus used to sometimes arrange himself in elaborate tableaux on the theme of "tricycle accident" without there ever being any real mishap. Michael has taken this idea and run with it.
He can arrange his Big Red Car, his Dog, his blue letters and some clothespegs for a good five minutes, then he completes the performance by "falling" backwards into the arrangement and dragging a small bike on top of himself as the piece de resistance. He then looks around for witnesses.