open up

Short definition from Wiktionary

Verb

1. 1
   To open.
2. 2
   To widen.
3. 3
   To reveal oneself; to share personal information about oneself; to become communicative.
4. 4
   To commence firing weapons.
5. 5
   To rain.
6. 6
   To begin running, driving, travelling, etc., at maximum (or faster) speed.
7. 7
   Synonym of cheat out (“tano face or d not until turn toward the audience more than would be natural”).
8. 8
   Of wine: to develop its full flavor a short time after being uncorked and poured.