I'm a bit sick, so the following text may not be entirely cogent, but:
The meme format used is a recent re-imagining of a fairly old and desperately unfunny post on a site called Memebase (which is almost exclusively populated by 12-year-olds), which ran along the lines of:
"Mum, can I have money?"
"For ice-cream?"
"yes . . . ice-cream"
actually buys weed
high time
In its new form, the format is used in reference to entirely unrelated events wherein either a predictable or barely controversial detail is made out to be a major plot twist, or an adverse outcome is implied to have been intentional (I admit it's still not great, but I guess that's just how internet humour works).
In short, what joke there is here revolves around the notion that Germany took out all those loans with the intention of losing the war and experiencing the subsequent economic turmoil.