Technically speaking it's masturbation...

Present Gracie stood beside the teacher desk, now topless with her shirt and bra discarded on the floor. She placed one of her sneakers against the back of the other one and prepared to kick it off.

"Hang on a minute." Future Gracie said, suddenly getting very close. She began to slide her finger down the centre of Present Gracie's chest, tracing the curves of one of her breasts. "I think you should keep them on. The whole 'naked except shoes and socks' thing is very sexy, isn't it? It's almost as if you-"

"-intended to leave the house naked." the two of them finished at the same time.

Future Gracie reached down and unbuttoned Present Gracie's jeans. She pulled them down to the knees, crouching down as she did so, while Present Gracie slipped her thumbs into the waistband of her panties and pulled those down as well. Future Gracie leaned forward and kissed Present Gracie's exposed pussy lips.

"Oops!" she said with a grin. "I guess I've just touched myself in class."

Present Gracie grinned back, then sat on the edge of the teacher's desk. Future Gracie pulled the jeans all the way down off her legs, followed quickly by the panties. Present Gracie spread her legs. Future Gracie stood up, pressed her body tightly against Present's and kissed her on the mouth. Present Grace wrapped her legs around the other girl's back, holding her in place.

Unknown to both girls, however, a small crowd were gathered just outside the classroom door. The teacher, Miss Nillson, jiggled the door handle ineffectively.

"Tsk, locked! I thought I'd left the key in here."

"Is class cancelled, Miss?" one of the students asked.

"No, no! Don't be silly. John, be a dear and run down to the janitor's office. He should have a spare key."

The two girls rested there, lips locked together, their tongues exploring each other's mouths as their bare bodies pressed together. Present Gracie reached behind her and swept the desk clean, sending papers and pencils clattering to the floor. She scooted further from the edge and leaned backwards. Future Gracie used her knees to climb up onto the desk, and after two quick kisses on the lips she began to travel downwards with her kisses, starting with Present Gracie's neck and working her way down towards the breasts. She ran her tongue over her left nipple, circling around the areola, while with her hand she reached up and gave the right nipple a pinch. Present Gracie released a moan of pleasure.

Future Gracie worked her lips lower, kissing her on the stomach, the belly button, and working down towards the crotch. She lowered herself off the table, and after giving her past self a wink buried her face in Present Gracie's crotch. She felt the tongue entering her most private of areas. She bit her lip and raised her sneaker-clad feet up onto the desk. Gently, so as not to hurt her, Present Gracie pressed her bare thighs against Future Gracie. She knew if she were in that position she'd want the same thing; the smooth warmth of a bare thigh pressed up against your face. She could feel the tongue inside her fondling her inner lips, brushing against her clitoris. She reached down and gently stroked Future Gracie's hair while her hips began to gyrate against the top of the desk.

It was at this moment that the door to the classroom suddenly opened. Future Gracie continued her endeavours completely unaware of this, while Present Gracie turned towards the door in shock as Miss Nillson and her mathematics class began to filter into the room.

Panicking, Gracie tries to reach for the Time Device...