Tattie is a Scots word for potato, and peelin is the same as peeling.
So what is tattie-peelin?
Well, in Scotland, tattie-peelin usually means speaking pretentiously, affectedly, or in a high-falutin' manner.
Of course, the trouble with the word pretentious is that its use is quite, well, pretentious - and the same sort of objection also comes with the words affected and high-falutin.
But tattie-peelin. Oh, that's an insult we can throw from a safe place with maximum scorn.
Book reviews? Och, half the time they're just tattie-peelin.
Ooh, I feel better already.
Thing Not To Do Today: tattie-peelin. This is Scots, but how it came to mean pretentious or prim I can't discover. My best guess is that it's something to do with the idea of being more concerned with surfaces and appearances than content.