Jeff Beacher vs. Justin Bieber -- Who'd You Rather?

Justin Bieber used lawyers to prove his Calvin Klein pics were the real deal ... and famous showman Jeff Beacher didn't touch up his spoof either -- not that you need a lawyer to know that.

Beacher got fake tatts to match Justin's and slipped into industrial strength tighty whities to show off his natural physique ... and to prove you don't need Photoshop to look sexy. But a hot chick always helps!

Beacher's taken on other famous posers ... like Kim Kardashian, David Beckham and Miley Cyrus -- and always emerged victorious.

So, question is ...