Zero Angel
Auror
I was only joking, and the joke wouldn't have been as funny if I'd put in historical periods and suchlike as well. Also I've never considered "period" to be slang for menstruation, just a word for it that's fairly normal.
Full stop is the British word for the punctuation mark Americans call a period. I believe it's also the root of the telegraph word STOP used at the end of sentences because morse code doesn't have punctation.
I was also joking. I did think it was a euphemism/slang however. It's supposed to be, "menstruation period", so just calling it a period is an alteration to the official, which I think counts as slang?
I figured it was British. Yins get all the cool words.