Donald Trump has never held political office, which explains a lot of his misconceptions about executive power and his forgetfulness Re the existence of Congress. And, since that means he’s never held an official title, it also gives Hillary Clinton a nice tool for undermining Trump’s swagger. Throughout Monday’s debate, Clinton called Trump by his first name, while he mostly called her by her appropriate political title: Secretary Clinton.

From her first recognition of his presence (“Donald, it’s good to be with you”) to her few pointed zingers (“Donald, I know you live in your own reality, but those are not the facts”), Clinton reduced her opponent to a casual first-name sparring partner. This is a man who loves his last name so much, he’s embroidered it on tie labels, stamped it on steaks, and splattered it in gold all over a chain of tacky hotels. Clinton’s refusal to use it must be grating at his quivering ego.

It also reverses the typical way politicians’ names are used in campaigns, wherein men get called by their last names (serious and professional) and women get called by their first (casual and low-ranking). In this debate, Clinton is the experienced, poised politician and Trump is the whining, pestering schoolboy. John Oliver proposed that we call Trump “Drumpf” to take the strength out of his name. Clinton’s strategy is better, because it’s not an explicit or petty insult; it’s his real name but spoken in a way that unmistakably says he doesn’t deserve her respect. She may not be able to convince Trump’s supporters that he’s a lying racist, but Monday night, she reminded them that he’s no white knight—he’s just Donald.

Read more Slate coverage of the 2016 campaign.