Mr.Spears is a character from Grease 2 . He appears in his class, taking pills while Principal McGee made the welcome PA announcements, her welcoming him back after he had returned from the hospital after taking leave for mental exhaustion. Apparently the 1960-1061 semester had been a real sweat, and sent him over the edge.
Mr. Spears was shakily gulping his pills as McGee continued overhead, some stuck to his lips, looking like he had buckteeth. As Mrs. McGee kept talking, Louis DiMucci snuck up behind Artie’s girlfriend, Vicki Hunt, who was dozing at her desk, a rat in his hands. Sharon Cooper, Aurelio, Roy, R.G., Willie Willard, and Francine watched with interest as Louis deposited the furry fellow onto Vicki's desk, and she shrieked. Mr. Spears' frayed nerves snapped, and he collapsed face-first on the desk like a marionette with its strings cut.
At the Luau, he had seeming been deemed fit enough to enjoy a relaxing day / night, watching the festivities - as long as nobody took him for a walk near the Pool of Enchantment.
Oops. By the side of the pool, Mrs. McGee took him for that walk. He was still shaky, googly-eyed, walking so unsteadily, he might as well have been made of rubber. As Mrs. McGee turned her attention away from him, Mr. Spears had drunkenly wobbled up the steps to the pool... and right into the pool. Mrs. McGee turned to see where he... wasn't... and saw his butt sticking out of the water, bobbing up and down.
After Lone Rider defeated the Cycle Lords, and revealed himself as Michael Carrington, Blanche Hodel, Principal McGee, Mr.Stuart, and Ms.Yvette Mason rushed to greet Michael, leaving the still-soaking Mr. Spears to wobble drunkenly, then collapse into a pile of human jelly.
It could be assumed that he retired afterwards, and Mr. Stuart permanently took over his place. To quote Mr. Spock (though Star Trek came out 5 years after Grease 2's year [1961]) "That would be the most logical option."