Rihanna flaunts butt cleavage...

So, Rihanna showed some serious butt cleavage during the Met Gala's afterparty at Up & Down nightclub in New York last night. I have two words. No, ma'am.

Rihanna wore Stella McCartney custom gold lame gown and Christian Louboutin gold metallic pumps:‬ 

Thoughts?