New Feat: Bewilderer

Urchins who become known as vexers may become so good at flustering other people that they can bewilder spellcasters. Urchin vexers are so clever they are able to jeer and fluster spellcasters while performing other actions, using only a bonus action to attempt to interrupt their concentration.

You can find the Urchin Bewilderer Feat in Homebrew options in DDB.