Listen for a while, then interrupt

"Fuck that was great!" Monica gasps, kissing Brian hungrily then giggling.. "I've got scratches on my ass again! If we're going to keep doing this we should leave a blanket out here."

"You're fucking hot," Brian growls, fondling her. "But we're going to get caught out here one day."

"Don't worry about it," she laughs. "The Headmistress runs later in the morning, and none of the girls who run get up this early. No one who matters is going to find out. Stop worrying Brian, I already told you this."

"I think the Dean runs too," Brian says, pulling out of her and kneeling between her thighs.

"Oh I hope so! You could both do me!"

"You're full of fantasies," he chuckles, standing up and helping her to her feet. He pulls up shorts, then helps brush the leaves and twigs off her bare ass.

"Mmmm, you know it! And I've been fulfilling some of them since you've been here 'Coach'," she says with a teasing smile. "You've been training me well."

He grins at her, then reaches out and pulls her squirming into his embrace. She turns her face up and stands on her toes to kiss him with greedy excitement.

Grinning, and for once acting on impulse, you creep back a few yards then step onto the path and start to jog towards them, deliberately making enough noise for Brian and Monica to hear you coming.