Sara, as much as she wanted to give in, still tried to keep the kiss light in the event of any unwanted visitors interrupted them. " I know you won't." Sara grinned. She could tell that Tracey was one of those girls that wouldn't say anything for fear that Sara would get mad. Which, she would, if Tracey told.
Moaning at the hands roaming her body, Sara pushed Tracey against the shelves more and pressed her body against her. She was getting very turned on. All the pent up sexual tension she had had in her was finally getting an outlet.
Enraptured in Tracey's touches, and her own touching, Sara barely heard the footsteps coming. At the last moment, she heard them and pushed Tracey back and pulled away from her and turning, not noticing if her sudden push made Tracey hit anything as McGonagall walked in.
"Professor." She said with an even voice, not giving anything of what she and Tracey had just done.