"Oof," Aziraphale says, and pulls a handkerchief to breathe into because the smell is just, classic Hastur. "Usually I'd get rid of this kind of thing with a couple blessings, but I don't think you'd stand up to an exorcism," he says. "Not to worry, I think I remember what to do," he says, voice muffled.

He goes to get a little salt, but then he remembers that Crowley doesn't keep books and so Aziraphale has no idea where he keeps the salt. Obviously, he's supposed to keep it next to all the occult books.

"Is your salt in one of the kitchen cabinets?" he asks, taking a wild guess because neither of them cook and Crowley hardly even eats when they go out. He also manages to find a bottle of wine will rummaging around, and pours them both a glass; they'll need it to get over the part where Aziraphale is going to try and get the last remaining bit of a Duke of Hell out of Crowley.