Andou: "You need to stick out your butt more and spank it, Oshida-kun! You'll never fool the Ooarai spies like that!" Oshida: "Damn you!" #OshidaBirthdayCelebration2023
References the OVA Taiyaki War @ 07:23, where Oshida does indeed bend over and slap her ass. I didn't catch it the first time, but she immediately frowns and blushes afterwards, indicating that it's all a ruse.