13. Rihanna f/ Chris Brown "Birthday Cake (Remix)" (2012)
It's not that weird to see Rihanna and Chris Brown together now, but when her "Birthday Cake" remix dropped, it was borderline shocking, and certainly a bit uncomfortable. Hearing Breezy scream, "I wanna fuck you right now!" in the middle song will be jarring, no matter what history he has with the other singer.