to prove to someone that you are the best and most powerful person on the planet
Person 1: Hey dude, you've got to kill someone in the school and show him who's boss of the school.
Person 2: Okay. I
Make it obvious who is in control.
Showing them who's boss is now necessary.
Angela
According to extensive research done by Abed Nadir in the show Community, Angela is the boss.
Who’s The Boss? Angela. Abed drove the professor crazy after proving that Angela was the boss.
A euphemism for jacking off. The man downstairs is referring to an individuals genitalia. By showing him who’s boss, you are beating him, aka beating off, aka jacking off.
Man, work has sucked today. I think I’m just gonna go home and end up showing the man downstairs who’s boss.