Wordnet 3.0
VERB (1)
1. 
 lose control of one's emotions; 
- Example: "When she heard that she had not passed the exam, she lost it completely"- Example: "When her baby died, she snapped"[syn: break down, lose it, snap]
WordNet (r) 3.0 (2006):
lose it
    v 1: lose control of one's emotions; "When she heard that she
         had not passed the exam, she lost it completely"; "When her
         baby died, she snapped" [syn: break down, lose it,
         snap]