I'm intrigued by the use of the linked words "off of" (where the second word is redundant) which I come across in American/Canadian books and speech now and again. I came across it again in a book I was reading in bed but I can't, of course, find the phrase again now. I've also noted in some newsgroup postings (not this newsgroup, I should add!) the word 'of' used instead of 'have' (eg "I should of said"). Does anyone know how these usages originated (although the second seems reasonably obvious)?