How come you never hear about the 2nd world countries, amirite?

its like the middle child there's to much going on with the first and third to pay attention

Actually we constantly do. They are just called developing nations, not second world, but it is the same thing.

Because the second world countries have become first world countries since the term was made up.

Yeah 1st world meant capitalist countries with large economies, 2nd world meant communist countries and 3rd world meant really poor countries. Since most communist countries crumbled we now use developed/developing countries.

First World: the United States and its allies.
Second World: the Soviet Union and its allies.
Third World: Non-aligned and neutral countries