A car alarm went to the store.
Cashier: Hello.
Car Alarm: BMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMWAAAMAAHAMAMAMAMAAMHMMMMMMMMAMAMAMMMMMMMMMMMMMAAMMAMMMMMMMMMMM BBEEEP BEEP BEEP BEEP BEEP BWAAAAMAAA!
Cashier: That will be 10 Dollars, sir.
A car alarm went to the store.
Cashier: Hello.
Car Alarm: BMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMWAAAMAAHAMAMAMAMAAMHMMMMMMMMAMAMAMMMMMMMMMMMMMAAMMAMMMMMMMMMMM BBEEEP BEEP BEEP BEEP BEEP BWAAAAMAAA!
Cashier: That will be 10 Dollars, sir.
Okay, listen up, buttercup. The joke is that the car alarm is 'talking' to the cashier, but all it can say is alarm noises. It's funny because it's unexpected and absurd. And you probably drive a beige minivan, just sayin'.