Interruption fads
An Interruption fad is basically exactly the name says: a fad that 'interrupts' the site in some way. There are two basic types of interruptions: those where the fad type is clearly spelled out in the title (most common with the Hassan fad), and those that aren't spelled out, making the presence of the fad a surprise.
Contents
Muhammad Hassan
Muhammad Hassan was one of the first interruption fads, and was based one the fact that the wrestler would interrupt people using his trademark yell.
NEDM
NEDM isn't always an interruption fad, but is often unexpected.
Thwomp
WHAT THE F BOMB
Kanye West
Kanye West interrupted Taylor Swift at the Video Music Awards, inspiring sites where he interrupts other people.
Horsedick
Spanish inquisition
Foot Doctor
Rickroll
The rickroll is based on the rickrolling phenomenon, where a person claims to be linking to one video and instead links to a video of Rick Astley's Never Gonna Give You Up.