When Demi Lovato stopped by 'Watch What Happens Live,' she played one bombshell round of 'Plead the Fifth.'

First, host Andy Cohen grilled her in a game of 'Shag, Marry, Kill' -- with the options being Justin Bieber, her ex Joe Jonas, and her 'X-Factor' co-judge Simon Cowell.

"I'd kill Bieber," she responded, laughing. "I'd kill Simon… and, f--- it, I'd kill Joe too." Hmmm… we're not so sure that's how the game works, Demi!

But the 'Really Don't Care' singer quickly backtracked, saying: "No, Joe and I are good friends. I'd keep him," though she soon admitted she wouldn't marry him, and wouldn't choose to "shag" him or any of the other options, either. (Considering one is her ex, another is her former BFF's on-and-off boyfriend, and the last is 33 years older than her, we can't say we really blame her.)

And as for what was the most scandalous thing she ever saw a former Disney star do? While we were all dying (dying!) to know the answer to this one, Demi had to keep her lips sealed.

"I can't answer that," she cracked up. "I plead the fifth."

But the final question was just a little more poignant, with the host asking the pop star why she unfollowed her former bestie Selena Gomez on Twitter.

"I plead the sixth, if that's in the game," she initially answered, before giving a genuine response.

"I think it's just one of those things where people change … and people grow apart," she explained.

Lovatics + Selenators, what do you think about Demi's response? Do you wish the singers were still best friends?

See Demi Lovato, Selena Gomez + More Celebs' Yearbook Photos

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