open up

To open.

To widen.

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

To commence firing weapons.

To rain.

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.