Sam and Eric are twins. Though they are two individuals, they are identified as one with the nickname "Samneric".
Their companions can't tell them apart so instead of using their names, their friends combined their names and used it to address any one of the twins.
Samneric do things together. They think alike. Basically, they are identical in all ways from physical appearance to their characters.
One that I can think of is Puppet, that is one of the Euphemisms in the book. they mean is that under Japanese rule Pu Yi was called Emperor but was actually controlled by the Japanese. And the second one would be <span>Forbidden City becaue it was not forbidden for those who lived and worked there. Hope thsi helps</span>
