Sloopy's, if it is still there, is located on Highland Avenue, just a couple of blocks south of Rosecrans, on the east side. Rustic wood decor - outdoor dining. It is the very first place I saw when we moved to Manhattan Beach in 1965.
And if you are in the area, and you enjoy Mexican food, there is a place called "El Tarasco" that makes awesome food for great prices. There used to be one on Rosecrans just east of Highland on the south side.
I don't know if Fat Burger is still there - but it used to be on the same block as El Tarasco.
AND......another great place in Manhattan Beach, called "Grunion's." Philly Cheesesteak Sandwiches to die for!!! It is on Pacific Coast Highway (Sepulveda), about 2+ block north of Manhattan Beach Blvd on the west side - kind across the street from a car dealership. If I remember correctly, there is a KFC next door, and if you turn west on the street next to KFC, then turn south on the first street and on the left there is the rear parking lot to Grunion's. The side door to Grunion's is on the south side of the building. You should see numerous Sun Tea jars sitting out near the door. Darts, pool, Skeeball, etc.
For breakfast, Uncle Bill's Pancake House if it is still there. It is on Highland Avenue, about 2-3 short blocks north of MBB, on the west side.