The stars of “Napoleon Dynamite” dropped by a freaking sweet Missouri diner over the weekend, where they gave customers a thrill … while rumors of a sequel to the iconic flick continue.

John’s Waffle & Pancake House co-owner Dona Ramadani tells TMZ … the tiny Kennett, Missouri joint was slammed Sunday … when an unassuming Jon Heder, Efren Ramirez and Jon Gries happened to belly up to the counter.

The trio from the immensely popular 2004 comedy film was finally noticed by a customer amid the commotion … and the fan floodgates opened. But it was all good … DR tells us the 3 were super chill and granted all snap and autograph requests … before leaving a “quite large” tip.

Seems the 3 were passing through after a Q&A screening of their flick in Paragould, Arkansas … and stopped at the diner that’s no stranger to celebs … as Dona told us that Kennett native Sheryl Crow drops by occasionally.

The visit raised some fan eyebrows after Efren — who played Pedro in the film — recently hinted to Collider that sequel talks are a reality … “Everyone wants a sequel — and I can say this legally, that the door’s not closed yet.”