Kraut and Limey are derogatory terms from the 1940s for Germans and English respectively.
The term kraut comes from sauerkraut, a popular German dish of fermented cabbage. Limey comes from the tradition in the British navy of supplying sailors with limes in order to combat scurvy.
James Lind had demonstrated that lemons could be used to cure scurvy. Assuming that lemons and limes would be equally effective, ships carried limes since they were more plentiful. However, limes proved far less effective, as they don't have as much vitamin C. The decline in scurvy associated with the use of limes was largely due to improvements in technology shortening naval journeys, giving scurvy less time to develop.