Hey, they haven't gotten kicked out yet! Also, Wei Wuxian is still laughing too hard to notice the approaching security guards.

"It's his given name," he finally gets out. All of the alcohol he'd walked off has already been replaced by the fizz of champagne, his cheeks flushed bright red under the light. "Wangji's his courtesy name, that's what everybody else uses, like -- Wuxian's mine but my given name's Wei Ying, right? So everybody calls me Wei Wuxian. Except him."

...Ah. Now he notices the security guards. Beaming, he salutes them with his half-empty champagne glass and a cheery wave.