This is a parody. The original song is from a musical, Chu Chin Chow, which enjoyed considerable success in London during WW1. As I recall the lyrics are about a Chinese laundry - the plot is based on a story from Scherezade. Since these days anything that refers to any sort of racial stereotype is offensive (simply defining a laundry as Chinese would get you into trouble) the words might be sonsidered rracist. At the time they were not. Unlike this parody.