歌詞の意味: 私は私のガールフレンドに私の人生のベスト アップ サイド ダウンを与えた

I went to the gym with my girlfriend and after a 2 hour routine you ended up very tired and horny and my girlfriend told me that she let me do whatever I wanted to her so I decided to give her the best Up Side Down of my life to relax.