The joke is that there are some people who think that by uploading themselves into a machine "to live forever," their consciousness will also be transferred, like when you travel by bus from one city to another. In reality, you "upload yourself," but that yourself is not you, but a copy of you. So, once the copy is done, you will still be in your original body, and the copy will "think" it is you, but it's not you. It's a copy of you! So, you continue to live in your body until you die, and, well, for you - that's it. You're dead. You're not living. You're finished. Everything is black. Void. Null. Done - unless you believe in the afterlife, so you'll be in heaven, hell, purgatory or whatever, but the point is, you're not longer on Earth "living forever." That's just some other entity who thinks it is you, but it's not you (again, because you're dead.)

This is represented by the parameters being passed by value (a copy) instead of by reference (same data) in the poster's image.

It wouldn't be you, it would just be another person with the same memories that you had up until the point the copy was made.

When you transfer a file, for example, all you are really doing is sending a message telling the other machine what bits the file is made up of, and then that other machines creates a file that is just like the original - a copy, while the original still remains in the first machine. Nothing is even actually transferred.

If we apply this logic to consciousness, then to "transfer" your brain to a machine you will have to make a copy, which exist simultaneously with the original you. At that point in time, there will be two different instances of "you"; and in fact, from that point forward, the two instances will begin to create different memories and experience different things, thereby becoming two different identities.

The first line passes the argument by reference, ie, the object itself.

The second line passes the object by value, ie, a copy.