The tennis player who is commonly referred to as "The Djoker" is Novak Djokovic. The nickname is a play on the word "joker" and is a reference to Djokovic's sense of humor and his on-court antics, as well as his Serbian heritage. Djokovic is one of the most successful tennis players of all time, with numerous Grand Slam titles and a record for the most weeks spent at world No. 1 in the ATP rankings.