Humor will not be tolerated!! -Portia

I have created an autobiographical comic, featuring myself and my sister's boyfriend.
I'm sure he's a great guy, I just feel incredibly stressed every time I spend any time around him. I'm going to be spending most of my time around him for the next week. Any tips?

Excuse yourself and go to your favorite mom and pop restaurant with a good book by yourself.
Go on a drive.
Go to Wal-Mart or whatever store you fancy and just walk around without buying anything.
Find a chore to do that is better done alone.
Apologize and claim the need for concentration on what you're doing.

Oh, I'm an expert at disappearing. I'm just going to be in a lot of situations over the next few days when disappearing will not be an option.

Remember that his over-friendliness is just as much a social handicap as your discomfort in groups. I do a lot better when I feel the people that intimidate/annoy me are acting out of awkwardness instead of malice. I can relate to that better, and forgive it more easily.

I usually physically hide behind Marduk when I'm with a someone like that. When he lets me, that is.

Be up front and honest. Something along the lines of, "I like you, but I have a limit of people I can take at a time, and sometimes I'll just need space. I'll communicate with you when that is." Like you say, he's trying to be friendly, and if you let him know that too much exuberance makes you uncomfortable, then most people will try to pare it back. But you've got to communicate that.

Good points about being up front and honest and all that jazz.

I find that crocheting or working a crossword puzzle/sudoku or doing something like that with my hands relieves some of the stress of those situations.

Did you survive, yay?