I don’t understand the message or joke of the cartoon itself, but George Donner was of German decent.
“The Donner party” is the name given to a series of events and dumb decisions in the 1840s that lead to 39 of the 87 American pioneers in the party dying from exposure, starvation, disease, and cannibalism when they ignored expert advice and took a “shortcut” to California, getting trapped in the snow.