wǒmen jùcān yǐhòu qù kǎlāOK.

Because X 以后 means after X.

So:

• 聚餐以后 = after having a meal together
• 下课以后 = after class
• 回家以后 = after going home

In Chinese, this pattern is very common:

• verb / event + 以后
• noun / time + 以后

So in this sentence, 聚餐以后去卡拉OK literally follows the pattern after the meal-together, go to karaoke.

聚餐 means to get together for a meal or to have a group meal.

It is more specific than just 吃饭:

• 吃饭 = eat / have a meal
• 聚餐 = eat together as a group, often for a social occasion

So 聚餐 usually suggests a gathering, such as friends, coworkers, classmates, or family eating together.

It can function as a verb:

• 我们晚上聚餐。 = We’re having a group meal tonight.

And sometimes it can also refer to the event itself:

• 这次聚餐很开心。 = This meal gathering was very enjoyable.

Because Chinese often leaves out repeated subjects when they are already clear.

So:

• 我们聚餐以后去卡拉OK。

is understood as:

• 我们聚餐以后，我们去卡拉OK。

But the second 我们 is unnecessary and would sound less smooth in many contexts.

This is very common in Chinese. Once the subject is established, it can be omitted if there is no confusion.

Chinese often connects actions just by putting them in order. The sequence itself shows the relationship.

So:

• 聚餐以后去卡拉OK
  already naturally means
• after eating together, (then) go to karaoke

You could add words such as 再 in some sentences, but it is not required here.

Compare:

• 我们先聚餐，再去卡拉OK。 = We’ll first have a meal together, then go to karaoke.
• 我们聚餐以后去卡拉OK。 = After the meal, we’ll go to karaoke.

Both are natural, but the second one focuses on the after X structure.

Because this sentence sounds like a plan, habit, or general statement of sequence, not necessarily a completed action.

• 了 is often used for completion or change of state.
• Here, the speaker is probably talking about what the group will do.

So:

• 我们聚餐以后去卡拉OK。 = After we eat together, we’ll go to karaoke.

If the speaker were describing something that already happened, they might say something like:

• 我们聚餐以后去了卡拉OK。 = After we ate together, we went to karaoke.

Or:

• 我们聚餐以后，就去卡拉OK了。 = After we ate together, we went to karaoke.

So the absence of 了 helps keep the sentence neutral and plan-like.

It can mean both, depending on what comes before it.

1. After X

   • 聚餐以后 = after the meal
   • 下班以后 = after work

2. Later / from now on / in the future

   • 以后再说。 = We’ll talk about it later.
   • 我以后想去中国。 = I want to go to China in the future.

So in this sentence, because 以后 comes right after 聚餐, it clearly means after.

Yes. Chinese usually puts time-related information before the main action.

Here the structure is:

• 我们 = subject
• 聚餐以后 = time phrase
• 去卡拉OK = main action

So the sentence is organized as:

• We
  • after eating together
    • go to karaoke

That is very typical Chinese word order. Time expressions often come before the verb they modify.

The Chinese part is pronounced:

• 卡拉 = kǎlā

Then the OK is usually said much like the English letters O-K, although pronunciation can vary a little depending on the speaker.

So the whole thing is commonly said as:

• kǎlā OK

This is a loanword based on karaoke. In Chinese writing, you will often see:

• 卡拉OK

In everyday speech today, many people also say:

• KTV

Yes, it is understandable and natural enough, especially in casual speech.

It literally means:

• go to karaoke

But in real conversation, people may also say:

• 去唱卡拉OK = go sing karaoke
• 去KTV = go to KTV / go sing karaoke

So these are all possible, with slightly different emphasis:

• 去卡拉OK = go to karaoke
• 去唱卡拉OK = go sing karaoke
• 去KTV = go to a karaoke place

Yes, absolutely.

These are both natural:

• 我们聚餐以后去卡拉OK。
• 聚餐以后，我们去卡拉OK。

The difference is mainly one of focus and rhythm.

• 我们聚餐以后去卡拉OK。 starts with the subject 我们
• 聚餐以后，我们去卡拉OK。 starts with the time phrase 聚餐以后

Chinese is often flexible in this way, as long as the meaning stays clear.

Usually 我们 just means we / us, but whether it includes the listener depends on context.

Chinese does not normally distinguish:

• we including you
• we excluding you

with different everyday words the way some languages do.

So 我们 could mean:

• the speaker and the listener
• the speaker and some other people, not the listener

You understand which one is meant from the situation.

In this sentence, if someone is inviting the listener along, 我们 probably includes them. If they are just describing a group’s plan, it may not.