#2 is possible, especially if you told the 2 jokes back-to-back in close succession, so the "it" refers to the "trying". But generally, #1 is best, so the "they" refers to the "jokes".

Both sentences are grammatically correct, but the choice between them depends on what "it" or "they" refers to. Here's the analysis: (1) "I tried telling a couple of jokes, but they didn’t come off." "They" refers to the jokes themselves. This sentence emphasizes that the jokes you told didn’t succeed—they failed to land or weren’t funny. (2) "I tried telling a couple of jokes, but it didn’t come off." "It" refers to the act or attempt of telling jokes as a single effort. This sentence suggests that your attempt at humor as a whole didn’t succeed. Which is better? If you want to focus on the jokes individually, (1) is more natural. If you're emphasizing your effort or attempt as a single action, (2) is better. Preferred in natural conversation: Sentence (1) is slightly more common, as people often think of jokes individually in this context. However, both are valid and convey a similar idea with a nuanced difference.

In the first sentence, "they" refers to the jokes themselves, whereas in the second, "it" refers to your delivery and attempt as a whole. Since "a couple of jokes" is plural, "they" fits better if you’re talking about the jokes. Also, instead of saying "didn't come off", you could say "didn't come across well" or "didn't land" or maybe "didn't go over well", as it would sound more natural.

The ‘they’ and ‘it’ are both correct but have different meanings. With ‘it’ you are saying that telling the jokes is one thing according to you, with ‘they’ you are saying that it wasn’t. On the other hand, I would never use ‘come off’ in an intransitive way like this. In my part of the English-speaking world it sounds almost vulgar. Natural are: - they didn’t work - nobody laughed - it wasn’t well-received I would personally only use ‘coming off’ like this, to mean ‘as a result of having’: Coming off a profitable year, we gave the staff a 10% bonus, our largest ever.

It is correct either way. Although "couple" is singular, you can choose to think of it as plural since it refers to two of them. You would naturally do this whenever you want to emphasize the individuality of each member of the couple. For example, "That is a nice couple. They get along well." "The couple were happy together." "The couple disagree a lot."