1.ดูจาก http://www.thefreedictionary.com/off
(of food or drink) having gone bad or sour ตัวอย่างเช่น this milk is off ของคุณดาก็น่าจะเป็น This jam is off.
2.Don't hold dvd like that , you're going to make some mark on it.
go off (FOOD) phrasal verb UK
If food or drink goes off, it is not good to eat or drink any more because it is too old:
This bacon smells a bit funny - do you think it's gone off?
off (BAD) adjective [after verb]
(of food and drink) no longer fresh or good to eat because of being too old:
This milk smells off.
I'd better eat this cheese before it goes off
3. when a computer or system suddenly stops operating: a computer crash
ปกติบอกลูก It's stuck.