A blowjob seems appropriate

"Well a blowjob would be adequate repayment." You tell her.

"Makes sense. You get her to suck dick for me, so I suck your dick." She says with a smile. You go off in search of an empty room so you don't have to brain wash the whole corridor. You quickly find an unused classroom.

You close the door behind Mary Jane and take a seat in the big leather chair behind the teacher's desk. MJ hurrys over to you and eagerly drops to her knees and starts to undo your pants. "Wait a minute," You say. "Let's do this right, take your top off."

"Oh, of course, how rude of me." She whips of her t-shirt, then takes off her white bra without you even having to tell her. She squeezes her big, bouncing tits together with her arms, "Is that better?"

"Yes, carry on."

She smiles and resumes undoing your pants. She pulls out your dick and eagerly licks it from base to tip. She wraps her lips around it and swirls her tongue around the tip before moving her head down. This high school senior is clearly no stranger to sucking cock. She starts to bob her head up and down, wildly, getting deeper and deeper with every dip of her head. She starts to gag when she goes too deep but she doesn't let that slow her down. You grab a fistful of her gorgeous red hair and encourage her down to the base. Her nose presses against you for a few seconds while she gags.