If you are going to get a hip flask, you should perhaps consider getting something like this Snapshot Camera Hip Flask at Graham & Green.
It doesn’t look like a hip flask, which is the first plus point. The second is that is actually looks like a vintage camera. You ‘fill it’ via the shutter button and if you are being particularly brazen, you can wear it around your neck, courtesy of its removable strap.
If you fancy one, Graham & Green has it now, priced at £42.