【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.