The bed weighs down where she sits, rolling Severus over. His face smacks into her ass, and he jolts to full consciousness, sitting up jerkily in bed. Irma seems to pay him no mind and continues pulling the ribbon off a little box.
Severus snatches it out of her busy hands and chucks it to the nightstand. "For goodness sakes, Irma, what time is it?"
"Dawn," Irma sniffs, before bending across him to reach for her present. "Which makes it Christmas, which makes me entitled to my gift."
Severus wrenches the box out of her grip again and hisses, "You are not entitled to anything, you silly woman." Severus holds the box tightly to his chest as he snuggles back beneath the covers, ready to catch up on the other five hours he'll need to function properly. When Irma moves to pry it from his arms, Severus rolls onto his stomach, head buried in his pillow and present trapped.
Irma makes a growling noise not unlike an angered cat and wrenches the blankets back, climbing quickly atop him. She straddles his hips and tries to fish under him, and he elbows her bony arms when she comes too close to success. Her naked front presses into his naked back and her breasts jiggle against him, almost distracting him. But he's Severus Snape, and he doesn't lose focus, ever. Irma hisses angrily beside his ear, "Severus, give me my present this instant!"
"You will wait until Christmas morning like everyone else," he growls back, but into the pillow, so most of it's muffled.
"It is Christmas morning—I told you!"
"Dawn is not morning!"
"Severus!" Irma beats on his shoulder blades with her delicate fists, which does absolutely no damage. She's too thin and too light for him to even notice she's there. Eventually, she gives up and rolls next to him.
He can tell she's still fuming, even without looking, because he knows her.
A few minutes later, when Severus has almost fallen back to sleep, she grumbles, "It's a ring, isn't it?"
Severus grumbles back, "Yes."