Girlfriend" is a song by Avril Lavigne, and was the lead single from her third album, The Best Damn Thing (2007). It was produced by Lukasz "Dr. Luke" Gottwald. "Girlfriend" became Lavigne's biggest hit in the United States, where it reached number one on the U.S. Billboard Hot 100; in Australia, where it topped the chart for 6 weeks, and in the United Kingdom, where it reached number two. A remix featuring rapper Lil' Mama was released in June 2007. "Girlfriend" was the subject of a lawsuit filed by songwriters for The Rubinoos, who alleged that the writers of the song plagiarised The Rubinoos' single "I Wanna Be Your Boyfriend".