1. once in a blue moon: seldom, not very often
- Once in a blue moon, I drive up Highway 1 until Carmel and take photographs along the way.
2. to have the blues, feeling blue: to feel sad, lonely, lovesick, depressed
- Everyday, everyday I have the blues / Ooh everyday, everyday I have the blues / When you see me worryin' baby, yeah it's you I hate to lose / Whoa nobody loves me, nobody seems to care / Whoa nobody loves me, nobody seems to care / Well worries and trouble darling, babe you know I've had my share ~B.B.King (Click here for song)
3. black and blue: bruised
- The poor guy's knees were black and blue after his first day of snowboarding.
4. blue blood: of royal ancestry
- Once the Brahn family arrived to the United States, they thought changing their surname to vonWaldenburg would make them appear as blue bloods rather than simple immigrants.
5. blue-collar: worker who performs manual labor, normally receives hourly pay
- Flint, Michigan is famous for its blue-collar working class that was once employed by General Motors.
6. out of the blue: unexpectedly, suddenly, (also, out of nowhere)
- Out of the blue, it started pouring rain while we were driving to the beach.
7. blue in the face: out of breath, lack of oxygen
- You can keep talking until you are blue in the face, but I will never buy a solar powered flashlight.
8. out of the blue and into the black: from bad to worse
- My my, hey hey / Rock and roll is here to stay / It's better to burn out / Than to fade away / My my, hey hey. / Out of the blue and into the black / They give you this, but you pay for that / And once you're gone, you can never come back / When you're out of the blue and into the black. / The king is gone but he's not forgotten... ~Neil Young (Click here for song)