The Weirdness Bubbles (also known as Bubbles of Pure Madness) are spheres of otherwordly energy conjured during the Weirdmageddon. As things made of raw madness, their effects are unpredictable, ranging from making whoever they touch go insane to altering the form of things inside their membrane.
In "Weirdmageddon Part 1" once Bill Cipher and his allies came to Earth, he brought forth these bubbles of madness for his own twisted amusement. One of them engulfs Sprott instantly driving him insane. As weirdness continues spreading more bubbles are shown floating all over Gravity Falls.
When Dipper and Wendy and are in a car trying to get away from Gideon and his team, they drive through some of the bubbles and as they enter, their heads become bird heads, then anime characters, bodies made out of cured meat and their live-action selves.
While both Gideon and Ghost-Eyes drive into the bubbles, they become 8-bites, women and black and white characters.
The bubbles come in many different colours and dimensions, and all have an oily glint on their surface.
- 218. "Weirdmageddon Part 1"