When Manny and Frida hear about the geeks secret hideout they decide to tell as many kids as possible and have follow then there for what they believe is a party, when it turns out that the geeks only use the house to play there games in peace. While the kids were partying they threw the geeks into the bathroom and told them to stay in there.
The house however actually belonged to the Mustache Mafia, the villians started attacking and not even El Tigre could stop them.
Marni and her friends still dressed as their heroes fooled the Mafia into thinking they were who they were dressed as, Marni using the sound system the kids brought to mimic the silver echos sonic attack.
She is voiced by Pamela Adlon.