The
mutual or mirrored behavioral traits a close friend, significant other, or family
member exhibits during a menstrual
cycle, or per the punctuation euphemism, "period".
"My
wife Jenny is on her period and eating tons of chocolate ice
cream, so I'm co-punctuating with her"
"My monthly cycle lines up with 3 of my sorority sisters, so we co-punctuate and ride out the bloodstorm together"
"My daughter and I have been co-punctuating, so we watched the Notebook seven times and cried a lot"