"The Best Fun I Ever Had" by Gilbert O'Sullivan is a song about reminiscing on a past relationship that brought the narrator immense joy and excitement. The lyrics convey a sense of nostalgia and appreciation for the love and fun that was shared. The song describes the former partner as the "best fun" and the "best girl" the narrator ever knew. The relationship was filled with love, happiness, and a deep connection. The narrator acknowledges that their partner taught them things they initially considered rude, suggesting that the relationship brought new experiences and perspectives. The lyrics also highlight the intensity of their love, comparing it to a "beautiful dream" and stating that even the drug LSD's effects couldn't replicate the excitement and thrill they experienced together. As the song progresses, the narrator reflects on the memories and good times they had together. There is a reference to the singing nun, a popular figure in the 1960s, which places the song's timeframe and adds to the nostalgic tone. Despite the joyous memories, the song takes a slightly melancholic turn. The narrator implies that there is a sadness they cannot hide when looking back on the past. This sadness may stem from the loss of the relationship or the inability to recreate the same level of excitement and happiness in their current life. The song also playfully references famous historical figures like Casanova and D.H. Lawrence, suggesting that even they would be amazed by the passion and intensity of the narrator's past relationship. Overall, "The Best Fun I Ever Had" portrays a bittersweet longing for a past love that brought immense happiness and excitement. It reflects on the memories shared and expresses appreciation for the profound impact that person had on the narrator's life.