Shofar, so good

This card comes with an optional joke inside:

Adam goes over to his friend Murray's house to schmooze. After a few hours, Adam says, "It’s getting late. It must be past midnight. What time is it?"
"Sorry, I don't have a clock," replies Murray with a shrug.
"You don't have a clock?!"
"Why should I? I have a shofar."
"A shofar? How can you tell time with a shofar?"
"Just watch," says Murray with a grin. He sticks his head out the window and blows a piercing long blast with his shofar.
All of a sudden windows in the street start opening. "What are you crazy?
Blowing a shofar?? It's TWO OCLOCK IN THE MORNING!"