I think (ry is more like our "etc". It seems, though, that (ry is more of a slang thing because in Japanese your sentences usually do not end like that and are more commonly expected to form a semantic unit that does not refer to something outside of the sentence ("etc" is short for "et cetera" which translates as "and the rest"). I could be wrong about this, though.

> It seems like DQN is equal to the word "n00b" in English slang.

No, I'd say "retard" is more like it.