This 1998 duet had all the makings of a smash single. First, it paired up rising then-teen female R&B stars Brandy and Monica — each of whom had notched four top 10 Billboard Hot 100 hits on their own, but not yet a No. 1. Second, there were rumors swirling that the two ladies weren’t exactly on friendly terms. Third, the lyrical content of the song was all about fighting over a man — perfect fodder for alleged rivals to sing about. The result? A No. 1 that lasted for 13 weeks at the top — at the time, one of only seven singles in the chart’s history to spend that long at No. 1.