Can you explain to me this phrase?

A little green salad on the side is good for you, me, and Mr. McGee - this what Barney from How I met your mother said.
I have no idea about the meaning.
Update: I don't think it's about food.
They talk about their challenge, Barney offers money Robin to say stupid phrases on TV.
So, maybe green salad is somehow connected with money?
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