That's a 3-chin Nelson, bet he's the only one in the family who can do that.
Speaking of Cory's Fundraiser for GKTW, who is the special guest who will be there? He's a professional musician (aside from Bob) from what I've gathered, and he's not featured on the above promo. Cory keeps referencing him and discussing practices but I have yet to catch the name.
Probably the Gijs van Winkelhof dude.