Which is better: being a weak nerd or a fat nerd?

Yes, I also prefer the heavier build. A heavier guy can at least defend himself if needed, while a skinny guy can't. Although, a skinny guy isn't always as weak as he seems. For example, Thai boxers, who usually don't weigh much, but damn, their speed and technique work wonders. And I wouldn't be so quick to call them skinny.