When we think of Justin Bieber, the word ass usually comes to mind. That’s why we’re not so surprised by this surprising self-posted Instagram pic. The Beebs has long flirted with public mooning with his droopy trouser suburbathug look. Now the flirtations have culminated into an all-out assault via social media. Just look at that ass! And then check out Justiin Bieber’s butt spilling out of what seems to be a respectable pair of black and white boxer briefs.