I found this in the staff notebook that lives by the door.

Apparently, a customer who was asked to leave wanted to register a complaint. The staff gave him a notebook and a pen and told him to write it down.

Written complaint

No indication of who the bartender was or why the person was asked to leave. No one was fired. Carry on.

UPDATE: According to a bartender at Fatso's, their establishment has a nearly identical note posted at their bar. Must be a serial complainer on the loose downtown.