Barney scolds Harris for all of the "Mishegaas" surrounding his book. Mishegaas is Yiddish for craziness and senseless behavior or activity
One of many instances in which Harris is depicted as a hypocrite. Back in Season 3, he convinced Wojo not to quit the force over having to wear a uniform for one day out of the year, telling him it's not so bad. Yet here, Harris flat out refuses to wear a uniform, thinking it's beneath him.