Big Trouble actor Ben Foster discovered just how strict Six Feet Under's bosses can be about secrecy - when he made a guest appearance on the hit TV show.

Foster, who once dated SPIDER-MAN beauty Kirsten Dunst, is playing LAUREN AMBROSE's love interest on the TV drama this season, and he's under stringent rules from the show's creator and producer Alan Ball to keep his mouth shut about the plot.

He says, "There's a lot I can't say about what's going to happen on the show. They put numbers on our scripts, so if anything shows up on the internet or in print, they can track us down."

The GET OVER IT star says the repercussions to castmembers, if they leak storyline information, include being sued and not being able to work with the show again.

Foster adds, "I think it's good business and good for the final product. Who is going to watch your show if you already know what's going to happen?"