Everybody was pretty busy tryin' to save the world. [But other people did have birthday parties. Of course, Sayori is the one he would have paid the most attention to, and she didn't have a birthday, as far as Sans knew. It seemed pretty rude to pry into that specifically.] You know what we were doin' last November. Before that was that one that only half counts, and I lost my memory in there too so I didn't even know when it was. Then before that... I was busy gettin' ready to do something dumb. And then we showed up here the November before that.

[He's been busy!]