What would happen if you put milk in a gas tank?

As milk is non-combustible as soon as the milk/gas mixture made it to the engine the car would stall. The gas tank and fuel lines would have to be drained and cleaned out but it probably wouldn't do permanent damage to the vehicle unless it were left to sit for some time when it could rust or coat parts that would then be very difficult to clean out. But, even though draining and cleaning the lines would be relatively easy it would probably cost hundreds or maybe thousands of dollars to diagnose and fix the problem. Do NOT do this, even as a joke, as doing so could land one in jail.