Dᴇᴀᴛʜ ᴀᴄᴛᴜᴀʟʟʏ sᴘᴇᴀᴋs ɪɴ sᴍᴀʟʟ ᴄᴀᴘs.

Looks better with a serif font, though.

EDIT: Oh, it actually depends on the publisher too, it seems. In the digital ones I’ve read, it was small caps, but in some others it’s apparently all caps.

Uncultured, clearly hasn’t read enough Discworld.