。
What would you do if a tiger got out of its cage?
Literal
By-chance tiger [subject-が] cage [from-から] exit-came-[conditional-たら] how do-[question-か]?
出てくる is the compound 出る + 来る ('come out, emerge toward [the speaker]') — the ~てくる direction auxiliary marks the action as moving toward the speaker. おり ('cage, pen') is typically written with hiragana or 檻. A vivid, scene-setting hypothetical.