First time I heard this chant was in Gezi Park events in 2013. Thousands of people were chanting “Polis simit sat onurlu yaşa/Police, sell bagels, live honorably”. Currently we dropped the police and started using it for other forms of corruption. It is especially being used for politicians, lawyers and spokespersons when they defend an obviously corrupt or injustice argument.
In Turko-Islam culture breadwinning is a holy deed and must come from a legitimate source. So in a way this saying assumes that a person must be doing this horrible act for money and reminds that there are many other ways of earning money (such as selling bagels on the street) than defending that horrible argument.