How does the Mutagen work, exactly?

[The Sewer Lord]

Originally Posted by RaphaeltheAwesome13

My theory:
Hamato petted a rat inside the store.
Turtles touched him.
Bradford got bit, Xever touched a fish. I read on some Nick site that if you touch a mutant it doesn't do anything.
Pete touched a human inside the Kraang lair.
Snake landed on some plants.
Tim got mutated and then stuck his hand into mutagen.

This is the best explanation.

Also, Ballstring touched some balls.