come off—
1. fall from smth. such as a bicycle, etc.:
- The horse refused at the first fence, and that’s when I came off.
2. become detached:
- When I lifted the jug up, the handle came off.
3. (of an event) take place; succeed:
- My friend’s marriage didn’t come off; his fiancée broke off the engagement.
go off—
1. = come off 3:
- They dotted lit bars and tables around the lot, and made sure the party went off without a hitch.
2. fall asleep or faint:
- He didn’t seem to be able to go off, so he went into the kitchen and made himself a cup of tea.
3. explode; make a sudden noise:
- Just as the burglar thought he was safely inside the house, the alarm went off.
4. (of food) deteriorate; become unfit to eat:
- This milk was fresh this morning, but it’s gone off.
5. (of gas, electricity, etc.) become unavailable:
- Just as the weather turned cold, the electricity supply went off.
6. (of goods) sell:
- I found that the place was one of no trade, and that my goods went off very slowly.