"PS: the other post-it note is clearly unfair haha, it's in room 5 (where you get the screwdriver), you have to go upstairs, walk outside on the sort of "balcony", and do a jump with mid-air control to reach the other side of the barrier, then you can walk behind the building and find it"
... I KNEW IT. I HAD A FEELING AND WAS EVEN TRYING THAT, BUT COULDN'T PULL IT OFF AND THUS THOUGHT IT WASN'T POSSIBLE.