Here's how I would envision it;

Myself;
I would arrive late, dressed in black pants, with a black shirt and a green sweater over the shirt, I would probably be wearing a scarf and possibly(unlikely but could be) a hat.
I would do what I do in every party, jack the booze and find a out-of-the-way place to sit away from others, which 10 times out of 10 will attract attention for some reason.

Elan would approach / see me and tell me I look like Charlie Brown, I would retort with something like "YEAH, WELL YOU'RE A... *looks down at self* F**k, I do look like Charlie Brown... *silence* Well played sir"
Then I'd chuckle and we'd shake hands, then he'd wander back into the party and quickly be swarmed by attractive young girls.

I would return to my corner and then probably attract some attention from one of the hostile/interested guys like Dobagoh / Catchandkiss, we'd banter a bit before drawing the attention of JDQ and Samantha, then the arguing would begin and gg.


Mere;
She would get lost on the way to the party and be substantially late.
But she left her place early to arrive early... failing miserably in the process.
She'd be wearing some jeans and a shirt, possibly a turtleneck because she'd say it was "cold", the turtleneck would naturally greatly display her rack.

She would not drink, but she would be around others who drink, she'd probably attract the attention of a couple of the lesser guys like Jakyobyo at first, then she'd be abandoned.
Some of the more evil guys would approach her and proceed to make fun of her, but she wouldn't realize that they were making fun of her. She would probably end up in the sack with someone she didn't expect, like Fujiou. They'd both be horrified.


Katsuni;
Would show up dressed in a massive wig, covering his/her body in such a way that it would be impossible to determine the sex of the individual.
Will not drink.
Will not smoke.
Will start long boring speeches at the drop of a hat.
Will not end up in bed with anyone.
Will probably be the first person to sit on food.
gg

Didn't someone make this same thread recently? I think it was Fruity.

I said then and I'll say it again, that would be a sad boring "party".

Who would be most likely to drink too much and black out before 9pm?

I wouldn't be horrified to wake up next Fuji.

The leaving early, arriving late, sound exactly like me though!
As for the clothes... I have never even owned a turtle neck.