Bunnies and big beach balls and pull-toy ducks. If very bright, it can alert one to danger, as when it is used on roadside signs. If very pale, it can remind one of lemon chiffon. It can be floaty, light, delicate. It may be the color of choice by children who draw the sun with radiating stick rays spreading into the blue sky.
Yellow rooms make people feel warmer and more comfortable.
Yellow used to be slang for chicken, which was slang for scaredy-cat, which was slang for fearful. Green is the one color nobody will agree on. Or is it a kind of sleazy motel carpet color, despised by all but the very fatigued traveler. Be careful of split pea green as it can sicken the viewer. Army issue green can evoke all kinds of unpleasantness.