Hermione/Snape (or maybe Sirius) in a mall

[Guest Uni]

They’re shopping in a mall, hermione called him “Sir” which I’m pretty sure it was Snape, but could also be Sirius. 
He buys her “slut red” lipstick after listening to the sales lady tell them she’s an earth tone palet. They end up sneaking into the back service hallways… he makes her strip and then hump the railing before taking her.  “What if someone sees us” “then you better put on a good show” and when they’re tone he hangs her underwear on a door and knocks before they run away.