Seamus & Hermione
Seamus hadn't really thought too hard about his costume. Really he'd spent about ten minutes thinking about it, and probably the same amount of time making it! Mummy! Easiest costume ever.
Though he doubted it would be as easy if the house-elves realised it was him who had shredded the bedsheets to make his 'bandages'. Wrapped up with a bit of flour on his face and some charcoal round the eyes and that was it. All he needed for a spooky costume!
With a goblet full of punch, Seamus wandered the room looking for someone to bother. Preferably Lia or Dean, but Seamus wasn't that picky! His eyes fell upon another of his kind (his kind being Mummy, of course) and he felt inexplicably drawn to her feminine figu--oh it was Hermione! He sidled up behind her and leaned against the wall, "Well, this is embarrassing."