Men might routinely forget birthdays and wedding anniversaries but I reckon there's one date every bloke has fixed unerringly in his mind: the last time he had sex.
It's not actually a date per se, more a total - in weeks, months, or god help him, years since he successfully ran the ferret.
If I was a Third World country, I'd have Rebecca Gibney flying in to shoot an ad for World Vision next weekend.
If it's a matter of mere days and the sexual counter has just been reset, most men probably don't even pause to consider this puny, unintimidating little number.
However, once the total has grown and can be measured in months, the figure sits in the back of a man's head ticking over like the timing device on an IED.
Me? It's been seven months since I scratched the awesome itch - after a split from my partner and child - and I can feel the one-year mark creeping up on me like a bloke with hairy wrists in a cell block shower.
For months my lack of sexual initiative hasn't bothered me, but now it's beginning to feel a little pathetic: I'm worried I might start collecting comic books or grow a ponytail.
Women probably have the same guilty awareness of their sex lives - in fact most gals seem to be able to blurt out the last time they bumped uglies as readily as a guy. I wonder, however, do they pay it as much heed as a man?
Let's be honest, if your average chick is truly desperate for a roll in the daffodils, she merely has to run the right colours up the flagpole at her local watering hole and she's pretty sure to find a taker.
I'm not saying the taker will have showered that day or have a bra size smaller than hers, but there's no shortage of blokes happy to help out a women in the pursuit of meaningless sex.
A desperate man? Well, he might as well be selling sausage sandwiches outside a vegan tantric workshop. He's usually going home with the esky still full.
At high school we had a rule that if a mate had gone 12 weeks without sex, he'd officially moved into drought conditions, such was the lack of moisture in his life.
That means I've progressed through an incipient dry spell, past mild and moderate drought conditions, into severe aridity and am now staring down an extreme rainfall deficiency on the Standard Precipitation Index.
If I was a Third World country, I'd have Rebecca Gibney flying in to shoot an ad for World Vision next weekend. Foreign Correspondent would be preparing a cover story.
So, to counter the growing pathos of being shagless, I have now engaged in an act of even greater pathos - going out specifically looking for, ahhh, love - just like when I was 19 - but at my age, your expectations are far lower and standards much higher.
Staring into blurred crowds of clubbers or drinkers who could be my offspring, I've found myself enacting almost forgotten rituals such as the rain dance (in front of a juke box about 1am) and cloud seeding, i.e. buying cute women vodkas, attempting to encourage storm activity.
However, unlike when I was 19, I now know that 3am is probably not the right time to find said "love" and it's OK to go home alone; sooner or later the rains will come, and me staying sober and avoiding pubs with juke boxes will probably make it more likely.
Lest you think this is a cry for help, let me say I do know there are people far worse off than me - millions of them in fact, who've haven't seen the rain for years, maybe even decades.
However, at least when you're married you get cuddles, cups of tea and maybe even the paper in bed on a Sunday. Sigh.