In conversations done among heavily otaku people, I often hear the words 2-jigen or 3-jigen used. I know its meaning: two-dimension and three dimension, except that it does not always seem to make sense. For example, in a conversation I found recently between two otaku people in Tokyo and Kyoto,
watashi wa 4-jigen kara kimashita. dakara 3-jigen de samishiku arimasen.
the first sentence, I can understand literally. But in the second sentence, what does it mean? The literal translation "(not) lonely in/at 3-dimension" does not make sense to me. How can I interpret that? I only hear this use among otaku people, not ordinary people. Is this a jargon among heavily otaku people? I just can't grasp the meaning!