Jon Bon Jovi thinks Justin Bieber is a word that rhymes with "glass bowl." And he wasn't afraid to say so -- quite publicly.

The veteran rocker isn't impressed with Bieber's tardiness to his London concerts recently.

"Every generation has guys that do that, none of that is new," Bon Jovi eye-rolled to the London Evening Standard (via The New York Post).

Bon Jovi has the perspective that the customer -- meaning the audience, in this case -- is always right, and of the utmost importance.

"They run the risk of disrespecting their audience members who have worked hard to pay for their ticket, to give you the permission to take two or three hours of their lives -- or in that kid’s case, 80 minutes of their lives."

"Do it once, you can be forgiven. Do it enough times and shame on you. They won’t have you back," Bon Jovi advised. “Then it just becomes a cliché. It’s really not cool -- you’re an asshole. Go to f---in' work!"