Foul up
Definition 1 of 2
Pro Tip 1/3Casual Expression
Used in informal settings, not suited for formal writing or speeches. 
I hope I don't foul up during my presentation tomorrow.
Pro Tip 2/3Plan Destruction
Emphasizes a mistake that ruins a well-laid plan. 
The surprise party was fouled up when the guest of honor arrived early.
Pro Tip 3/3Confusion Cause
Highlights its use when an action creates disarray or misunderstanding. 
Instructions were clear until Mark fouled up the explanation.