To get a general idea of its size, I'd say it's similar to a regular size wine bottle, but without the slim taper.
Hiding depends on who you're hiding it from and what level of search. If it's from a roommate, a cleaning crew, or someone who probably wouldn't be seriously looking for it, try anywhere that people are unlikely to bother to look for anything. Inside an empty suitcase. Inside an old camera bag (if you can put a camera in with it). On a back shelf behind a stack of old text books, tax returns, or other things of no interest.
If you're hiding from spouse, parents, who are more likely to do a more thorough search, I'd try a locked tool box, brief case, etc.
If you're hiding from a nosy sibling who will do a police-style search, you're better off just not having one at all.
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