1. To do something, such as signing in or stamping a time card, to officially record the end of a shift or day of work. A noun, pronoun, or reflexive pronoun can be used between "punch" and "out." We'd like to remind all employees to punch out at the end of their shifts. Failing to do so can cause delays in payroll. Sarah's going to stay behind for a little while, so she asked me to punch her out. I keep forgetting to punch myself out when I'm the one closing the restaurant.

2. To render someone unconscious with a punch. A noun or pronoun can be used between "punch" and "out." A: "Oh man, what happened?" B: "Well, you and Bart were fighting, and then Bart punched you out." I swear I'll punch out anyone who tries to mess with you. Sarah punched him out when she found out he'd been stealing from her.