In old Warner Bros. cartoons, one common gag is a single can of paint that contains an elaborate pattern, like plaid, which can be applied to a surface with a single brush stroke. It’s funny because ...

A coffee spill leaves behind a dark stain around the puddle’s edge when it dries. But as drops of paint dry, some look like “fried eggs,” with “yolks” of color surrounded by pristine white halos, ...