If you continue this conversation for too long, two angry nuffians will appear, one of them probably with a penguin demanding memes
Now back onto more important topics: From tags on the thing it seems that the girl is actually Selene who is the Pokemon sun and moon female main character if they were black and the cousin is someone who has been pulled out of nowhere. Female pokemon trainer + Trainer Selene appear as tags on both versions of the meme with tags I could find. Plus that appears to be what the four chan post was talking about as well. It's from before the game released as well so not much detail was known!
This is a guided bullet. This is a guided T64 tank round. and these are bullets with adjustable speeds!
I never know how you find those things, I tried reverse image searching and found nothing... >.> Nice to know it has altered words though... Still, looks cute enough to give a shot to~ Edit: Seems like there is no fantranslation available and only official translation... Guess it goes to the list of stuff to buy later.
Usually it shows the meme sites if not outright the result. Those meme sites usually have the sauce. The visually similar image option sometimes give the original image if it's edited before, and/or slightly more complete version to re-search with. As long as the page is intact google is quite effective narrowing it down.