Justin Bieber Threatens Suit Over GIF … I’m Jacked, Not Puny!

EXCLUSIVE

Justin Bieber is mad a website made it look like Calvin Klein pumped up his muscles using Photoshop, and except he gets an admission he’s going to court. 

Justin’s team fired off a demand letter — obtained by TMZ — threatening breatheheavy.com with a defamation case for posting a GIF showing Justin transformed from mildly muscly to jacked.  

The Biebs and company say…