Bart Defending Himself Against the Bartender

Okay, look here, you slowpoke. The joke is a visual pun based on how 'BART' is literally inside the word 'BARTENDER.' So, the meme imagines this as a dramatic, violent confrontation where 'Bart' is trying to stop the 'Bartender' from coming at him. You must spend all day chewing on your keys if you didn't get that immediately.