It's not just the plot for Adam Sandler's new flick "That's My Boy" ... it's the real-life story of Mary Kay Letourneau ... and now TMZ has learned, M.K.'s former student believes the movie is all about him and his naughty teacher ... and he loves it!
For those of you unfamiliar ... Letourneau was arrested in '97 after it was discovered she was having a sexual relationship with her 13-year-old middle school student Vili Fualaau.
Letourneau was found guilty of statutory rape and sentenced to six months in jail ... and agreed to no longer have contact with Vili. She broke the agreement in '98 and went back to jail for 5 years.
By the time she was released, Vili was an adult ... and a judge allowed the two to see each other again. They got married in 2005.
But back to the movie -- Vili hasn't seen it yet ... but after getting a slew of calls from friends, he and M.K.L. are planning a date night to watch what he believes is their love story -- with creative license, of course.
"Maybe this movie won't suck as bad as the last few films he made," Vili tells us ... but optimistically adds, "We're talking about my life and a young boy banging his hot teacher ... what's not to like about that?!"
Vili and M.K.L. hope to catch the flick this weekend -- we'll give you their review Monday.