The message of this source is that Germany is that the Treaty of Versailles is unfair and that Germany is being harshly treated and forced to accept the terms.
In the source I can see a man, who represents Germany, being squeezed by a hand, which represents the Allies. Germany is being forced fed “peace terms” by the Big Four who represent the USA, Britain, France and Italy . It also says “worth millions a pill” which suggests they are forcing them to pay reparations. The Big Four are saying “You’ve got to swallow it whether you like it or not”.
From my own knowledge I know that many Germans, and also some British people as shown by the author, thought that the Treaty of Versailles was very harsh on Germany, especially as they were forced to accept the terms and not allowed to negotiate. One of the terms was that they had to pay £6.6 billion in reparations to the Allies.