This is really amusing me today. I tried it after reading the MN 4 year email which said that a 4 year old could repeat a (I think) 4 syllable word. Tried it on ds and indeed he could. He enjoyed it and has asked me to say more and more difficult words for him to try and it is very very funny IMO
best so far:
disestablishmentarianism
I tried "anti-disestablishmentarianism" but he just said "anti......schtabment.....OH BOTHER "