Jared McCain was hitting the high notes after going under the knife on Tuesday ... crooning his favorite songs in a post-op karaoke session -- from Drake to Lil Baby, Sabrina Carpenter and Tate McRae!!
The 21-year-old shooting guard went on his Instagram right from his hospital bed ... saying he felt "really good" following his procedure to fix his UCL tear he suffered last week.
With his eyes half open, McCain hilariously treated his 1.