The term is typically used to describe a family of fairly well known tricks that can overload the analog electronics in the CRT monitors of computers lacking hardware sanity checking (notable examples being the IBM Portable[1] and Commodore PET.)
In early PETs, writing a certain value to the memory address of a certain I/O register (POKE 59458,62[3]) made the machine able to display text and graphics on the screen 106% faster.
This was accomplished by disabling a "wait to print to screen" safeguard designed to reduce static/noise by preventing the shared VRAM from being read by the display at the same time as it was being written to by the CPU.
Despite the static, some games designed for early PETs included this POKE in their source code in order to benefit from the faster graphics.
[1] When the PET range was revamped with updated hardware, the video rasterizer circuits were redesigned to run at a faster speed and without the need for a "wait to print" safeguard.
Instead, performing the old trick on the new hardware led to strange behavior by the new video chip, which could cause signal contention and possibly damage the PET's integrated CRT monitor.