Hey, Joe's planning on arranging a gathering for Halloween

[NamelessKing]

Is this dialog natural?

A: Hey, Joe's planning on arranging a gathering for Halloween at his place. We're gonna have a dinner on Friday, you down? It'd be great if you could wear a costume, and since you're a nerdy guy I'd suggest you dressing up as a mad scientist.
B: Sounds good man. I'm not really into costumes, but I can tag along.
A: Sure, it's optional if you don't feel comfortable, just wear something casual.
B: Thanks man, see you on Friday.

 

[emsr2d2]

Is this dialog natural?

A: Hey, Joe's planning on arranging a gathering for Hallowe'en at his place. We're gonna have a dinner on Friday. You down? It'd be great if you could wear a costume, and since you're a nerdy guy, I'd suggest you [STRIKE]dressing[/STRIKE] dress up as a mad scientist.
B: Sounds good, man. I'm not really into costumes, but I can tag along.
A: Sure, it's optional. If you don't feel comfortable, just wear something casual.
B: Thanks, man. See you on Friday.

Note my changes above.

Is it natural? Well, it's natural if you're a teenager or at least a relatively young person. No one I know would use "you down?" or refer to other people as "man".