Instructions:
1. Open facebook and download both your profile picture and your cover picture.
2. Open both pictures side by side in a text editor
3. Scroll down a random amount on the second text and copy a chunk of text. Scroll down a random amount and past (or replace) the text.
4. Check the original image and evaluate changes.
5. Repeat process
6. If the change is too drastic or undesirable simply undo the changes in the file and save again.
7. Again, if the change is too dramatic it might happen that the computer no longer recognizes the file. Simply undo changes and save.
8. Continue the process.
9. Once the image has been modified to your taste save one last time.
UPDATE:
This is a response by the comments:
At the beginning I had stricter rules of what to change or what to remove. I first started searching for specific letters or dates and removing them. This made the image way too corrupted and I could no longer open it. It is clear that I don't understand what the code means as I am modifying it, therefore I take a more exploratory approach.
Here a video of me redoing it and getting a very different result.
I am making decisions as of where to add/subtract/change code, as well of if continue that path or go back. Still since I don't understand what I am doing I really don't have any real control. Often my goal in the process is to see how far I can go before the computer tells me I went to far and refuses to open the file. Not sure if I am cooperating with the machine or against it.
Finally, something strange that happened to me was that even that my computer was able to properly display the image, once I uploaded it to my website it could't be displayed. In another moment my glitch actually got unglitched...
There are other methods I have used to generate glitch visuals. One of my favorites cannot be found.