It is an outdated british slang phrase meaning "it is ready" or "it will be happen". It comes from old film industry slang, when the film was ready to be released.
Journalist: This movie took so long that it was almost forgotten...
Film director: Everybody made an excellent job, the film is in the can.
"She's in parties. It's in the can."
Bauhaus - lyrics She's in parties
When a play, movie, or other visual art reaches a very emotion point, and someone kills the mood, typically by droppingsomething. Coined during Q-Artistry's 2014 run of Zurkis Grimm.
I was supposed to be hired by Jon but now that Ian is the new manager he gets to make the decision. No news yet, they are just kicking the can on my employment.