The most spectacular example of this I've ever seen was a developer writing Java that only ever used single-character identifiers.

As in the following style:

    class D {
        public A foo(B b, C c ) {
            D d = b.x( c );
            return new A(d.f(1));
        }
    }

You might be wondering: what happens when he gets to "z" and runs out of identifiers? No problem! He just kept going thus: aa, ab, ac, ad, etc... I saw code up to "dh" or somesuch.

He had perfect job security... right up until the startup he was working for imploded because nobody could collaborate on that code.