When you're running out of words to describe the phrase "go off the wall," don't worry because there are many synonyms available that you can use. You can use expressions like go crazy, lose control, flip out, or freak out when someone does something unexpected or erratic. You can use colorful and descriptive phrases like go ballistic, go haywire, go bananas, or go bananas in the head. You could also use slang versions like go nuts, go loco, or go ape. Whatever synonym you choose, it will help you more expressively convey that someone is acting wildly or going out of their normal routine.