To skip work
In German there is a saying "making blue" (blaumachen): This means "to skip work". The expression origins from a time, when painters had to mix the colors by themselves and could not just "go to the next store" or "shop online" to order what they need. Blue was rare in nature and creating the right blue was time consuming and involved working with mercury or bromine - both highly poisonous substances. Painters skipped work often after being exposed to those influences.
Therefore "blue" was reserved for painting kings and until today, there is a tone of blue called "Königsblau" - the blue of the kings. It goes so far, employers had to use blue letters to fire someone from work which then is the "blue letter" - the letter of resignation.
Today we have to luxury to use blue just out of the tube or pot, but we should always value this color with special consideration, as once upon a time famous painters died or got sick from creating it.
"a waterfall in the rain forest of Cebu" - painting on square wooden plate.