A semi-rigid sleeve for a bottle that is open at both ends and can be inserted downward onto a freestanding bottle so as to cling thereto as a second skin. The sleeve generally comprises a cylindrical body defined by a resilient sheet of semi-rigid material (preferably high-density plastic) open at both ends and having an axial slit running end-to-end, the body being defined by an inward axial curvature and compression-formed with a shape-memory characteristic to normally retain a smaller (furled) first diameter which can be forcibly expanded by parting along said slit to a larger (unfurled) second diameter. An optional rubber coating may be applied to the interior/exterior of the body for insulation purposes. The smooth semi-rigid exterior surface of the bottle sleeve provides a superior advertising medium and outstanding multi-color graphics can be applied by thermoset printing processes, resulting in far more eyecatching graphics than traditional foam koozies.