Complex sentence: On November 13,2012, During the MDNA Tour's second performance at Madison Square Garden in New York City, Madonna was joined onstage by Korean entertainer Psy and together they performed a mashup of the song and "Gangnam Style".
Split into simpler sentences: On November 13,2012, during The MDNA Tour's second performance at Madison Square Garden in New York City, Madonna was joined onstage by Korean entertainer Psy. Together they performed a mashup of the song and "Gangnam Style".