Karrueche Tran -- Grand Marshall at Celebrity High School ... on a Tractor!!!

Karrueche Tran returned to her high school victorious, serving as the Grand Marshall of the Fairfax High School Homecoming Parade ... and she was transported by John Deere.

Karrueche got big applause Friday night from people in the stands, which is impressive. Fairfax High has a slew of celeb alums, including Demi Moore, David Arquette, Iman, MIla Kunis, Steven Adler, Slash, Phil Spector, and so many others.