I know I shouldn't be laughing but I am!! I can't even imagine trying to keep a straight face at this party. In my brain I would have been thinking...I wonder what century he was doing this light saber stuff because it certainly isn't this one!!!
Seriously tho, I think you handled the situation just fine! The guy that got up and left because he was laughing so hard, did too, actually!
As for me, this is the exact reason why I prefer to be a wallflower at parties. I am so painfully shy around people I don't know (and sometimes even people I do!), everything always comes out wrong and/or I get choked up on the words.
Usually I will just shake my head and agree and/or throw in some agreement sounds - I don't know how to write those - and then quickly move on to someone/somewhere else.
Thanks for putting the picture in my brain of the 400+ lb guy playing with the light sabers!! I'm going to go pray for forgiveness now for laughing!! That is, if I can stop!!