You insist on using the word Wossname to fill gaps in your wossname, vocabulary, rather than just looking it up in the wossname, in spite of your knowledge that it drives everyone reading your blog/post/email (or listening to you) to absolute wossname. (Distraction? Yes, that's what I said.)
Thometimeth you lithp like the Igorth, even though you know itth irritating in the ecthtreme. Jutht becauthe you can. Thorry.
You mispronounce anything vaguely Latin- or French-sounding. Nobbly-esse obligay, imp arse and raisinned eater are just some of your victims. No-one else ever realises these are Pratchett references - you always have to explain, only to be asked: "Pratchett? Who's Pratchett?!"
You recount every Pratchett joke you remember, and feel bad because everyone assumes they're yours, as you don't want to have to explain constantly (see previous). This doesn't mean you're happy about this. Some Pratchett jokes, like elves, are bad. So everyone assumes it's your sense of humour, and shuns you accordingly.
You honestly don't mind ir-chatting or blog-posting with people named Death121, Gr8Wizzard or Angua99.
You quote idly from your favourite novels and are depressed when no-one else knows the punch-lines, or which book it's from. On the other hand, your friends think you're odd. Very odd.
When you accuse people of speciesism, no one knows what you're talking about. (Again).
After you spend ages explaining the concept of dwarf bread to people, they agree it is rather cute and funny. They still think you're odd, though.
Your second favourite philosopher ever is . . . Terry Pratchett.
You understand the ending of Strata.
(If you don't know about the ending of Strata, you obviously don't read enough Pratchett.)
You frequently compare fictional police detectives unfavourably with Sam Vimes, who is obviously the best copper ever conceived in the pages of a whodunnit. Who cares about the stupid Dirty Harry references? Fabricate mei deum! Er. Or something.
You use the phrase "Trust me on this" way too often. You just can't stop yourself.
You recite Feegleisms with the Scottish accent.
You think in footnotes.
Occasionally, you say "Quoth, the raven!" and giggle to yourself. This is a sign you may need the roundworld equivalent of dried frog pills. Or you'll go bursar...