
Louse up
Casual Usage
Use 'louse up' in informal settings, like conversations with friends, not in formal writing. 
Negative Outcome
'Louse up' implies a mistake leading to a negative result, showing disappointment or frustration. 
Colloquial Origins
Originates from 'louse' being a pest; 'louse up' metaphorically means making a situation 'pest-like' or troublesome. 