Justin Bieber is pretty bad at keeping his own appreciation of illicit substances a secret (hence all those pot pics), but he has no problem mocking viral video stars struggling with their own issues.

'Intervention' star Candy Finnegan is mad as heck at Biebs for an Instagram video he posted this week, mocking an 'Intervention' subject named Rocky Lockridge. Lockridge was a boxer who once defeated Bieber's own pal, Floyd Mayweather, before succumbing to demons and spiraling into drug addiction. His addiction led to a stoke and Lockridge now walks with a cane.

Lockridge was a subject of the A&E series 'Intervention,' and his sobs made him an Internet celebrity. However, when Bieber -- who, as we previously mentioned, is pals with Mayweather -- mocked him, it contained a bit more of a meanspirited vibe.

Now, TMZ reports that Finnegan is flamin' mad, telling press, "We can only pray that when, not if, Justin needs an intervention ... that someone as loving as Rocky's family will be there for him." Bam!

Here's hoping Bieber -- and the rest of the Internet -- will be more understanding someday that addiction is a disease, and not something to be mocked.