What is shit posting & trolling

Is there an actual definition of shitposting? Is it possible to create a program whose input is a post (+ context) and the output is isShitpoast T/N?
Related (and what made me think of it): what is trolling? Back in my Internet days (capital I), trolling was very strongly defined. Nowadays, trolling seems to be whatever the author disagrees with.

Guido van Rossum waited. The lights above him blinked and sparked out of the air. There were trolls in the Internet. He didn't see them, but had expected them now for years. His warnings to Cernel Sussman were not listenend to and now it was too late. Far too late for now, anyway.
Guido was a Python maintainer for fourteen years. When he was young he watched the SICP students and he said to dad "I want to write a programming language daddy."
Dad said "No! You will BE KILL BY TROLLS"
There was a time when he believed him. Then as he got oldered he stopped. But now in the /prog/ board of the W4C (R.I.P. ;_;) he knew there were trolls.
"This is Sussman" the radio crackered. "You must fight the trolls!"
So Guido gotted his browsar and posted a thread.
"HE GOING TO PISS US OFF" said the trolls
"I will flame at him" said the cybertroll and he fired the forced indentation arguments. Guido BAAAWed at him and tried to made him give up. But then the thread was locked and they were trapped and not able to flame.
"No! I must flame the trolls" he shouted
The radio said "No, Guido. You are the trolls"
And then Guido was a forced indentation of the code. Thraed over.

"It's time for some ENTERPRISE QUALITY!" Asakura cheerfully cried as she conjured the spirits of the JVM, producing a flood of boiling-hot coffee that rushed its way towards The Sussman, who stood motionless, parentheses continuing to issue from his wand like electromagnetic radiation.
"You think your turkey solutions can stop me?" The Sussman said calmly before lowering his wand, forming the pool of parentheses now gathered around him into a sharp pointed cone aimed at Asakura. Suddenly he shouted "LIIIIIIIIIIIIIIIISP!" and the parentheses shot forward into the waves of coffee, pushing the boiling hot liquid back towards where it came.

"Nooooooo....." her cries became weaker as she became engulfed in the dark brown liquid. Everything turned black and I felt as though I had fainted. I awoke to a familiar voice.

"...before we do that for the next couple of lectures we're gonna be talking about..."

I opened my eyes and raised my head to find myself seated in a lecture theater. I glanced at the clock and found that I had missed most of the lecture. "Damnit! I was looking forward to the first lecture of the last semester of 6.001!" I thought to myself.

HAX MY ANUS ONII-CHAN

Our evaluator for Lisp will be implemented as a Lisp program. It may seem circular to think about evaluating Lisp programs using an evaluator that is itself implemented in Lisp. However, evaluation is a process, so it is appropriate to describe the evaluation process using Lisp, which, after all, is our tool for describing processes. An evaluator that is written in the same language that it evaluates is said to be metacircular.

The metacircular evaluator is essentially a Scheme formulation of the environment model of evaluation described in section 3.2. Recall that the model has two basic parts:

1. To evaluate a combination (a compound expression other than a special form), evaluate the subexpressions and then apply the value of the operator subexpression to the values of the operand subexpressions.

2. To apply a compound procedure to a set of arguments, evaluate the body of the procedure in a new environment. To construct this environment, extend the environment part of the procedure object by a frame in which the formal parameters of the procedure are bound to the arguments to which the procedure is applied.

what is an actual definition though? How does it compare to a regular definition?