Robert De Niro may have had his boxing fists up in defiance at Donald Trump on Sunday night’s Tony Awards, but that wasn’t even the most interesting feud of the night. In an exchange just bitchy enough to be worthy of Theater’s Biggest Night, Tony-winning actor Neil Patrick Harris and  Crazy Ex-Girlfriend star Rachel Bloom appeared to have mixed it up over Harris’s professed ignorance as to who Bloom actually is.

Bloom was performing backstage hype duties on CBS’s Tonys telecast, kicking us to commercial and chatting with backstage celebs, that sort of thing, while hosts Josh Groban and Sara Bareilles were busy elsewhere. Decked out in a black-and-white ensemble and a teeny tiny hat, Bloom was living her musical-theater fantasy and showing why the entertainment industry (screen  and stage) should be paying attention to her as  Crazy Ex-Girlfriend heads into its final season.

Somewhat less impressed was Neil Patrick Harris, a multi-time Tonys host who, this year, was enjoying the show from the comfort of home with his kids. Employing that age-old passive-aggressive tactic that annoying parents have been pulling for years, where they attribute some witty observation to their kid to make them sound preternaturally smart and funny (which in turn flatters the parent; it’s a whole thing, we can’t get into it), Harris tweeted “Who is the woman in the top hat backstage at @TheTonyAwards? Gideon remarked that she says ‘like’ and ‘oh my god’ a lot. I’m confused…”

So many questions as to the intent of this tweet!

• Was NPH trying to be bitchy in an “I don’t know her” Mariah Carey way? If so, why?
• Does NPH somehow not know who Rachel Bloom is? And if so, doesn’t he have friends he can text?
• Was NPH making a (bitchy, passive-aggressive) point about grammar do’s and don’ts for his 7-year-old son Gideon’s benefit?
• Are he and Bloom actually friends and doing a bit?

Whatever the rationale, Bloom managed to find the time to tweet a blisteringly perfect response: “I’m a big fan of yours. We’ve met numerous times and my husband, Dan Gregor, wrote for ‘How I Met Your Mother’ for 5 years. Notably, he wrote the episode where your character finally meets his father.”

SNATCH. THAT. WIG. RACHEL.

Harris’s meek reply ? “Indeed! Well said. Thanks for the reminder. How was backstage?” ? seems to indicate this wasn’t some kind of bit, making it one of the most awkward and uncomfortable (but also wonderful) celebrity slap-fights we’ve witnessed in a minute.