Tom Cruise Curses Out Rob Pattinson!

Tom Cruise has no problem cutting Robert Pattinson down to size -- or cursing him out!

The two superstars butt heads in a new promo for the MTV Movie Awards.

But Cruise, 47, isn't recognizable: Suri's papa is back as "Len Grossman," the fat, balding foul-mouthed Hollywood producer character he played in Tropic Thunder.

When the 24-year-old Twilight hunk tells Grossman he might shampoo his famously dirty hair for the awards fest, Grossman gives him some tough love.

"Your filthy hair made you a star! Your filthy hair sent my fat-*ss kid to Space Camp four times!"

Watch the hilarious clip now (above)!