A "school bestie" refers to a person who is your closest friend at school. They are someone you spend a lot of time with, share secrets with, and trust. Full definition
I bonded with my high school bestie over a box of Kix cereal, and months later, she invited me to Thanksgiving dinner with her family! (healthynibblesandbits.com)
On the piece, I can see the block my elementary school was on, the location of the neighborhood market where I worked for one week before getting a job at a jewelry store, and the spot of my grade school bestie's house. (bedknobsandbaubles.com)
My high school bestie, Susan is an incredibly talented home chef with impeccable taste in the kitchen. (naturalsweetrecipes.com)