In a recent speech about the national debt, Obama said it's time to "Eat our peas".
What does it mean - where does it come from?
The phrase "eat our peas" is not, as far as I know, a historical metaphor. However, according to the context given by CBS, President Obama was telling the nation that they had to buckle down and do what might hurt but would be good for them.
To add further context and explanation, the sentence also referred to "pulling off the Band-Aid". When you need to take off a Band-Aid, you have to rip it off in order to get it over with. The president was saying the same thing twice.
Edit: There is more discussion of this metaphor here, as it is not a usually accepted metaphor. The author writes,
I take it that the pea-eating metaphor is intended to indicate that all sides must take an unpleasant political hit to settle the debt issue. They won't like it, but it'll be good for them.
I am not sure where the saying comes from in terms of its origin, but in my opinion it comes from the fact that children don't like to eat peas but are made to because it is good for them. They are green, and gross, and have a yucky texture to them...my mom still hates them! So I would use it to refer to something that I would have to do in a begrudging manner, knowing that it was good for me but man did I hate having to do it!!