I don't know how many times the long termers/old timers here have tried to emphasize the need to keep stress low. That stress can be emotional, physical, mental/cognitive, and nutritional (alcohol, caffeine etc)

A high stress event can undo weeks of recovery. It can require days to weeks to recover from just the stress event before getting to where you can continue your concussion recovery.

A social occasion can be a stressor that leads to brain overload resulting in poor decision making. Think of all the bad decisions made while buzzed. PCS is like your brain being in a constant state of buzz. Decision making is always at risk.