colors and feelings / things they are associated with, symbolize
Red: symbol of fire/love/anger, shows embarrassment/anger, dominance; Yellow: related to sunshine, signals attention, easy to see; Blue: sky/sea/water, sadness
weather-related idioms (e.g. feel under the weather)
throw caution to the wind, be down to earth, be as fast as lightning, be a ray of sunshine, be in deep water, go down a storm, have your head in the clouds