[syn: start, protrude, pop, pop out, bulge, bulge out, bug out, come out]
3.  exit briefly; 
- Example: "He popped out for a quick coffee break"
4.  come out suddenly or forcefully; 
- Example: "you stick a bill in the vending machine and the change pops out"
WordNet (r) 3.0 (2006):
pop out
    v 1: appear suddenly; "Spring popped up everywhere in the
         valley" [syn: pop out, burst out]
    2: bulge outward; "His eyes popped" [syn: start, protrude,
       pop, pop out, bulge, bulge out, bug out, come
       out]
    3: exit briefly; "He popped out for a quick coffee break" [ant:
       pop in]
    4: come out suddenly or forcefully; "you stick a bill in the
       vending machine and the change pops out"