Colin did not laugh. Instead he thought, Tampons have strings? Why? Of all the major human mysteries - God, the nature of the universe, etc. - he knew the least about tampons. To Colin, tampons were a little bit like grizzly bears: he was aware of their existence, but he'd never seen on in the wild, and didn't really care to.
John Green (2008). “An Abundance of Katherines”, p.59, Penguin