I do this on purpose all the time, much to the 'fake' annoyance of my 12 year old granddaughter! (Everyone else I know just ignores it now). She's always correcting me and I act totally innocent and bemused at her reaction. Lol! For instance, instructions are 'destructions', "I beg your pardon?" is "I bag your puddin'?", "Excuse me" is "Exsqueeze me". I deliberately use Spoonerisms too, which she also likes to correct me on! Par Cark, Fog Dood, and so on. I've been doing it so long it's totally natural and I don't even think about it now, which can sometimes be embarrassing when speaking to a complete stranger...... 