Uh... you can't? But seriously. You can't. What you CAN do, I suppose, is make such a good friend of the woman, learn to ride her moods, and then, several years from now, when you are both sharing a white wine and beet salad in some trendy restaurant that charges for water, tell her that there are times when her high good spirits can annoy her team.
Crazy people need to be corrected just like anybody else, but the guidance needs to take place in an atmosphere of love, respect and enormous tenderness. People who are incredibly insensitive to others are often those who are MOST sensitive about themselves. Go figure.
Until then, I'd say put up with the good moods, try not to feel too bad during that bad ones, and realize that these swings have NOTHING at all to do with you. If you don't take crap like this personally it tends to annoy you less.
Last updated December 20 2007: 1:13 PM ET