It’s how she is mostly disgusted with him playing what he does while the people around her are also kind of bitter at first and then by the end they are all dancing and she is like “really? you like this?!”
There’s a really good lesson here which is you can do just about anything as long as the voice leading is good. Your ear is drawn to a very fluid pop melody on the top line and doesn’t care quite as much about the absolute crazy shit that’s happening underneath. I know I’ve heard this song countless times and could definitely hear modulations, but I always assumed it was maybe like one or two chord substitutions and whole step modulating between keys. Holy shit at the actual chart.