end up (doing something)

This phrase is used for telling the final result of something. It can be used when telling stories, like in the example above. It can also be used for predicting the future consequences of an action:

If you keep missing classes, you're going to end up failing your grade and having to repeat it.

Another phrase that's similar to "end up" but more casual is "wind up":

After we left the bar, I wound up going over to James's place and sleeping on the couch.

the (number) of you

When you're talking to someone who's part of a group of people, you can talk about the group like this:

Where did the two of you meet?

I've known the three of them since they were little boys.

You can also talk about a group that you are part of with the phrase "the ___ of us":

The three of us went out that night to an art gallery.

collaborate with (someone)

"Collaborating with" someone means working together on something that's creative or intellectual. Here are some examples of collaborations:

• three scientists can collaborate on a scientific paper
• a singer and a songwriter can collaborate on an album
• two companies can collaborate to releaase a new product together

Use "collaborate" together with "with" and "on" like this:

I collaborated with him on a paper a few years ago.