Complex sentence: He calls Jamie's mother to set up an excuse to get Jamie to go to Grand Central Station thinking she will be picking her mother up, and arranges to have a flash mob dance to "Closing Time" set up to surprise Jamie at the station.
Split into simpler sentences: He calls Jamie's mother to set up an excuse to get Jamie to go to Grand Central Station thinking she will be picking up her mother. He arranges to have a flash mob dance to "Closing Time" set up to surprise Jamie at the station.