Flask
Kirk holding McCoy's flask
A flask was a small flat container used to hold beverages, usually alcohol.
In 2154, Klingon Doctor Antaak gave a flask to Denobulan Doctor Phlox while the latter was enduring imprisonment in Qu'Vat Colony. However, Phlox chose not to drink from the flask. (ENT: "Divergence")
Phlox's captor, General K'Vagh, had a flask of his own, which was filled with alcohol. At one point, he used it to toast the bravery of two Klingon warriors under his command. Phlox also declined to drink from this flask. (ENT: "Divergence")
In 2255 of the alternate reality, Leonard McCoy drank from a flask, presumably to calm his nerves about the shuttle flight he was taking to Starfleet Academy. He offered some to James T. Kirk, who drank from it. (Star Trek)