I saw this phrase on a forum today, from an AmE native:
1. Will you relax already!?
which I take to be the equivalent in BrE of e.g.
2. Will you just relax for one moment!?
I've often noticed this AmE use of trailing "already". How does it work, exactly? When can you use it? And is it a recent usage?
BobK is correct, "already" originated as a Yiddish expression. It is used for emphasis, or to express exasperation. Sometimes we add "and be done with it" to add extra emphasis.
"I really like John, but I don't know if he likes me..."
"Why don't you just tell him how you feel already!"
"That cheesecake looks so delicious, but I really shouldn't have any...."
"Oh, just eat a piece already, and be done with it!"
Thank you very much, Bob and Ouisch!