A student kept bugging his friend, "What time is it?" Finally, his friend complained, "Why don't you get a watch like the rest of us?"
"Why do I need a watch? There is always someone around to ask."
"But what can you do in the middle of the night, when you are alone and need to know what time it is?"
"That's easy—I blow my shofar." (A shofar is a ram's horn, blown on Rosh Hashanah and at the end of Yom Kippur, which sounds like a wailing voice.)
"You what?"
"I blow my shofar. Whenever I wake up and need to know the time, I open the window and blow it very loudly. Literally within seconds, I hear someone yell, 'Are you crazy? It's 2:45 in the morning!'"