Why doesn't my British neighbor understand the slang I use?

[Joshua]

I said to her and I quote, "I'm sorry I didn't called sooner, Janie. It's just I had to shoot down so many girls and guys' responses on facebook" She actually thought I was doing something on facebook with a gun, I had to explain to her that "Shooting someone down" means saying no to them
I kind of find that endearing about Janie that she doesn't understand my American slang
Although I do understand her slang, she just doesn't get mine
she's like a year younger than me and she transfered to the local university when I went

[Olivia]

Because she is British I'm gona guess that they do not use the same slang as we do

[quatt47]

Nothing about being British, it's because she doesn't understand the terminology as she probably doesn't use Facebook.

[Expertdinner216]

Not being a facebook user, I wouldn't have understood what you meant either if you had not explained. Have you ever thought of translating your colloquial conversation into plain English when speaking to people who may not understand the vernacular of your generation?