This Monday, Rihanna celebrated born day No. 24 by releasing the remix for “Birthday Cake”—the 90-second banger from her latest album Talk That Talk. To the surprise of many the track featured an unlikely partner: Chris Brown—who returned the favor by having his ex-girl jump on his remix for "Turn Up The Music." But really it turned up the noise. Shock! Horror! Outraged open letters!

What Breezy did to RiRi years ago is no secret, and even though that whole awkward restraining order is now a thing of the past, their collaboration is an odd one to say the least. On the plus side, both tracks are legitimately dope.

The whole brouhaha got us thinking about other weird duets and features that made folks wonder WTF? Yes, Michael Jackson really did a song with Eddie Murphy, and even Jay-Z and Nas squashed their beef and hit the booth. Find out where Rihanna and Breezy’s “Cake” ranks on our list of 10 Music Collaborations We Thought We'd Never See....

Written by Brad Wete (@BradWete)