>>>In Serbian, you can be in the tree only if it has a hollow trunk. And there's a verb for "climb down".
>>>
>>>Conversely, when you get INTO a bus, where are you?
>>
>>I suppose you're probably at home studying all the information you can get about the bus.
>
>So you open a door, get in, and all of a sudden you're on it?

Depends on what you're into.