Carefully.
As they weigh nearly nothing the effect of gravity is minimal.
You see the ceiling as smooth, flies see it as a very rough surface.
There are plenty of "handholds" for their feet with hooked claws at the end.
Your head will be touching the ceiling
He painted the ceiling of the Sistine chapel.
no ship flies the American flag upside down when leaving port
hummingbird
It gobbles up!!
Lionel Ritchie: Dancing on the Ceiling
the artist who sings the upside down during 80's new wave is TWO MINDS CRACK.
The fly makes contact with the ceiling with its front legs. Using the momentum from flying, it swings the rest of its body and it's legs attach to the ceiling.
No it has not yet, but you could possibly build it on your ceiling, but it would never work out the way you would plan as a regular toilet. (but technically a space toilet could work upside down)
Centipede
It is not a protest, when the American flag is flown upside down it is a warning that the base has been captured.
House flies have specialized adhesive pads on their feet that allow them to cling to surfaces like glass or ceilings. These pads secrete a sticky substance that forms a strong bond with the surface, enabling the flies to walk upside down without falling off.