What is Bill O’Reilly even talking about?

Last night, while the O’Reilly Factor host was imploring Donald Trump to return to Fox News’s Thursday Republican debate, things got deeply personal and weird.

This merits a bit of play-by-play. At first, Trump seems amused that O’Reilly brought up their top secret special milkshakes, of which Trump apparently owes O’Reilly 17. As O’Reilly says, “I bought you so many vanilla milkshakes. I bought you so many vanilla milkshakes—you owe me,” Trump cracks a smile and says, “It’s true.” But a few moments later (below), Trump seems annoyed, telling O’Reilly, “Well, even though you and I had an agreement that you wouldn’t ask me that—which we did—I will, therefore, forget that you asked me that. Because I told you, upfront, I said: ‘Don’t ask me that question.’” 

There’s a lot to unpack here. Was Bill O’Reilly making a Kelis reference? Did he think his milkshakes will bring Trump back to Fox News’s yard? There Will Be Blood? Do Bill O’Reilly and Donald Trump go on 50s-esque malt shop dates together? Why is O’Reilly the only one to seemingly ever pay for milkshakes? Why does Trump only drink vanilla milkshakes, when everyone knows that those are best as special treats you only have every now and then? And why did they agree not to talk about this specifically before the interview? Is “vanilla milkshake” code for something else?