Diddy -- An Absolut Schmuck?

So everyone knows that Diddy is the new $100 mil brand-builder (don't say spokesman!) for Ciroc vodka -- but a source tells TMZ that the folks who make Ciroc are pissed that he's still quaffing 1800 Tequila like water.

Puff stands to make a fortune from his multi-year Ciroc deal, but the man does love his 1800 -- we hear he's been ordering it everywhere from Nobu to Prive, and Ciroc's parent Diageo -- who paid him to pump out the hooch -- isn't happy.