The Situation SIX-FIGURE TUXEDO DEAL

No prom is safe -- TMZ has learned The Situation just locked down a brand new deal to endorse a line of TUXEDOS ... and if that wasn't shocking enough ... we're told it's worth SIX FIGURES.

It's all for a company called FLOW Formal -- a New York-based tux manufacturer -- and CEO Brian Weintraub tells us, Sitch is the perfect spokesperson ... because the company is trying to target a younger demographic.

Weintraub adds, “This is great for us and great for the industry. [Tuxedos have] become an old man thing."

The line is called ... wait for it ... "The Situation" -- and it includes tuxedos, slim-fit shirts, and accessories. It's expected to launch in February 2012.