The kids aren't being bullies [as BKF noted], they're teaching. What they're teaching is: Strength isn't everything.

Also, the tinier and cuter the girl, the more outright vicious they can be when given permission to be violent [see the testimonies of Renfaire workers at or near "Smite the Knight" activities. The pinker the dress, the glitterier the fairy wings, the more outright RAGE they have inside their teeny tiny bodies]