7. Madonna, 'Into the Groove'
"Into the Groove" first appeared in Madonna's 1985 movie Desperately Seeking Susan, but the dance song didn't appear on the actual soundtrack; she held it back for a re-release of her breakthrough album Like A Virgin later that year. It became one of her biggest hits, though she doesn't like it much these days. "I feel retarded singing that song," she told Rolling Stone in 20o9. "But everybody seems to like it."