I love a good Spoonerism. I'm always doing it, and I often make them up, like nooks and crannies, and crooks and nannies, beggars can't be choosers and Cheggars can't be boozers (Keith Chegwin RIP), and flat cap for cat flap etc. It drives my wife insane – she thinks it's childish, I disagree!
My best unintentional one was when having a few drinks in the garden with my brother one night and he brought out a very hot homemade salsa and tortilla chips. It was really hot and I meant to say, "jeez, my gum's burning" but instead said "Jeez, my bum's gurning". Quick as flash, he replied "It will be in the morning!" Cue drunken falling about on the floor…………….
So, what's your best Spoonerism?