What he meant probably is exactly what you said. I believe that in the scenario I created, Japan would be the one everybody makes fun of because it switched sides
I think there are important differences between Italy changing sides IOTL and Japan changing sides ITTL.
That is Japan declared war on Germany on 23rd August 1914 before the Battle of the Marne. Italy remained neutral until May 1915 when I assume it looked like the Entente was going to win and the Entente had made them a better offer.
Having written that, what if the Japanese Government decided to wait and see who won the opening round before declaring war on the Central Powers? And what if the Germans did a bit better? That is they didn't win the Battle of the Marne outright, but were able to occupy the Pas de Calais and the front line ran from the English Channel, along the line of the Somme as far as Amiens, then to Montdidier and then to Compiegne where it would join the River Aisne? And/or things don't go as badly for the Austrians in Galicia in 1914?
If Germany and Austria-Hungary looked as if they were in a better position in September 1914 would that be enough to persuade some countries that joined the Entente or remained neutral after August 1914 to remain neutral or join the Central Powers ITTL.
The more countries that do join the Central Powers the more that are likely to join because of the
bandwagon effect/domino effect/snowball effect.