In my case this stands for pre-menstrual tolerance.
I don't get PMT, you would hear me say, and I don't outwardly. I don't crave much more than an extra egg, I rarely get mardy, my horniess is almost unbearably high to very high!
I do however, become extremely headstrong, almost a checks and balances from my head to heart to loins.
As an example, I can look back at each time Quiet boy and I took a breather, and each time it was two days before my period.
My period is due today and the last two days have been filled with putting my house so to speak in order with efficiency that Mary Poppins would be envious of.
Noticeably my tolerance levels all but disappear. Unfortunately I tend not to notice that until it's too late!