Eating what we call "the Mickey Head Ice Cream Bar"...well, Dh actually calls it a "$3.00 dilly bar". It's the one thing that is completely and totally non negotiable!
ETA: not that I think about it, we always get fish and chips from the UK counter service on our first afternoon/night and sit in that garden area behind the buildings. It's the signal that "we're at the world, let the games begin"