What is the meaning of Open_up?

To open.

To widen.

To bring up (a topic etc.).

To reveal (oneself); to share personal information about oneself; to become communicative.

To commence a literal or figurative battery of attacks.

1. To commence firing weapons.

   To commence firing weapons.

   To rain.

   To berate; to begin shouting at or insulting someone or something.

   To begin running, driving, travelling, etc., at maximum (or faster) speed.

   Synonym of cheat out (“to face or turn toward the audience more than would be natural”).

   Of wine: to develop its full flavor a short time after being uncorked and poured.

   Source: wiktionary.org