I'm taking a risk this year, and have my backup costume all ready in case this one doesn't work out.
Here's my costume for Halloween...
I'm going to grow my hair out a bit and then color it a brownish yellow color.
I will also wear an oversized, starched white button down shirt.
Over the shirt, I will wear a grey suit, no tie.
When I get to the party, I'm going to spend a lot of time in the kitchen near a plate of cookies. When people ask me who I am, I will say, "We'll get to that in a minute..."
I will then pull out a huge collection of white paper featuring raunchy chat transcripts and begin asking them questions about their online chat names and why they are actually at the party. I will ask them if they're there for 'Sexsh'.
Later, I'll introduce myself as Chris Hansen from Dateline NBC and then let them know that I'm doing a program about adults who visit teens for sex. I'll ask them if they have anything else to say. Afterwards, I'll let them know that they're free to go.
I'm actually kind of excited, because I pretty much have his voice down pat. I think this costume would be doable even if you didn't have the voice down. The key is reading off various raunchy chat transcripts and/or possibly showing pictures of the guy with a parrot on his wiener.