This game was invented by Lewis Carroll, the creator of Alice in Wonderland. The players have to turn one word into another by changing one letter at a time. Each change must leave a recognisable word.
It's easy to change DOG into CAT. DOG goes to DOT, then to COT and finally to CAT. Changing PIG into STY takes a little longer:
Here is a selection of doublets for you to puzzle out: if you like, you could have a race to solve them between all the passengers. Turn
HATE into LOVE GIVE into TAKE HAND into FOOT HOT into TUB APE into MAN COW into HEN
SICK into WELL FLOUR into BREAD BEER into WINE