I'm at the part where the store manager is complaining to the Watch that a fake Hogfather is giving away gifts in his shop.
Unfortunately, Mr Crumley wasn’t in the right receptive frame of mind. He stood up and waved a shaking finger towards the top of the stairs.
‘I want you to go up there,’ he said, ‘and arrest him!’
‘Arrest who, sir?’ said Corporal Nobbs.
‘What for, sir?’
‘Because he’s sitting up there as bold as brass in his Grotto, giving away presents!’
Corporal Nobbs thought about this.
‘You haven’t been having a festive drink, have you, sir?’ he said hopefully.
‘I do not drink!’
‘Very wise, sir,’ said Constable Visit. ‘Alcohol is the tarnish of the soul. Ossory, Book Two, Verse Twenty-four.’
‘Not quite up to speed here, sir,’ said Corporal Nobbs, looking perplexed. ‘I thought the Hogfather is s’posed to give away stuff, isn’t he?’
This time Mr Crumley had to stop and think. Up until now he hadn’t quite sorted things out in his head, other than recognizing their essential wrongness.
‘This one is an Impostor!’ he declared. ‘Yes, that’s right! He smashed his way into here!’
‘Y’know, I always thought that,’ said Nobby. ‘I thought, every year, the Hogfather spends a fortnight sitting in a wooden grotto in a shop in Ankh-Morpork? At his busy time, too? Hah! Not likely! Probably just some old man in a beard, I thought.’
‘I meant . . . he’s not the Hogfather we usually have,’ said Crumley, struggling for firmer ground. ‘He just barged in here!’
‘Oh, a different impostor? Not the real impostor at all?’
‘Well . . . yes . . . no . . .’
‘And started giving stuff away?’ said Corporal Nobbs.
‘That’s what I said! That’s got to be a Crime, hasn’t it?’