I'm assuming another unwritten rule is that there must be no trickery with the bottle itself?
I.e. no taking a "wide mouth" bottle, filling it with some stuff, then somehow heating/narrowing the bottle? (Perhaps that isn't physically possible anyway, without leaving visible evidence)
I.e. no taking a "wide mouth" bottle, filling it with some stuff, then somehow heating/narrowing the bottle? (Perhaps that isn't physically possible anyway, without leaving visible evidence)