1) Cockney rhyming slang for see 2) Enjoyable pastime 3) Favorite thing 4) Matter to be reckoned with 5) Personal choice 6) Personal preference 7) Preference 8) Preference, figuratively 9) Preference, so to speak 
Cup of tea is London Cockney rhyming slang for urination (pee).
[n] - an activity that you like or at which you are superior
bag noun an activity that you like or at which you are superior; `chemistry is not my cup of tea`; `his bag now is learning to play golf`; `marriage was scarcely his dish`
a task, topic, person, or object well-suited to a person's experience, taste, or liking.