We think we know why Megan McArdle was on a bit of tear yesterday, especially in relationship to the Center on Budget and Policy Priorities graph: Brad DeLong corrected one of her errors and it set off a little party in the comments. McArdle makes a special guest appearance in the comments as well. Go, enjoy! We will have more later, after our work is done.
ADDED: Paul Krugman also corrects McArdle. If McArdle keeps this up she will overplay her hand and destroy her marketability. If she is fired she'll just be replaced by a lower-paid, younger, slightly more clever version, but maybe some day the people who hire the shills will become pariahs as well.