This cartoon was published in a Punch magazine (a British publication) in 1936. It was a satirical commentary on Germany's violation of the Locarno Treaty, which was signed in 1925. In the treaty, Germany had pledged never to go to war with other countries. The cartoon depicts Germany as a goose stepping on the Locarno Treaty while wearing a helmet and carrying other weapons like rifles and a machine gun. In the mouth of the goose is an olive branch (a symbol of peace) which carries a note on which is written "Pax Germanica". This shows that the cartoonist thinks that Germany wants to establish an empire by imposing its military will.
This cartoon was published shortly after Hitler remilitarised the Rhineland in March 1936. The lines "Goosey Goosey Gander/Whither Dost Thou Wander?/Only Through The Rhineland/Pray excuse my blunder" is a sarcastic verse to suggest that Germany's actions in the Rhineland were insincere and done under false pretenses.
A German reader would certainly find this cartoon very insulting because the bird associated with Germany is the eagle and the cartoonist's use of a goose was probably to mock the goose-step, which was a German military drill.