"BLIT" (acronym of Berryman Logical Image Technique) is a 1988 science fiction short story by the British writer David Langford.
It takes place in a setting where highly dangerous types of images called "basilisks" (after the legendary reptile) have been discovered; these images contain patterns within them that exploit flaws in the structure of the human mind to produce a lethal reaction, effectively "crashing" the mind the way a computer program crashes when given data that it fails to process.
As he is approaching a gay pub to spray the "Parrot" onto a wall where those exiting will see it, he is caught by the police — and in the process accidentally kills four of them with the stencil.
All they can do is fine him for spraying graffiti, so after beating the locations of all the "parrots" he painted out of him (disguised as a "fall down the stairs") they lock him in a holding cell to be released the next morning.
The main characters, all school children, form the "Shudder Club", where they take turns looking at an illicitly obtained non-lethal BLIT image to see how long they last, inadvertently vaccinating themselves against it.
[14] John Clute noted that "Like the fractal caltrap it describes, David Langford's stunning "Blit" gives off a steely medusoid glare; and one is very glad the tale is so short".
[20] "Basilisk hacks" that affect the mind of any transhuman who perceives them are a primary method of operation of the Exsurgent Virus in the science-fiction/horror role-playing game Eclipse Phase.
The trope of vampires being vanquished by signs of the cross is attributed to a basilisk specific to them: perpendicular lines (something not found in their prehistoric habitats).