Last night, I attended my friend Nic Rad’s gallery opening for his awesome PeopleMatter series of blogger and media personality portraits.

Then, once the gallery kicked us out, a slew of us headed down to The Half King for drinks.

We started out with a dozen people at the table, and as folks bid the crowd adieu, they left cash on the table to cover their drinks and tips.

Eventually, the bill came, and everyone tossed dollars into the pile. And I said to Nic, “I bet we have $90 of cash here.”

I was close. We had $92. Which, including tip, was slightly less than half of the $190 bill.

My guess wasn’t based on eyeballing the money pile. It was, instead, based on the First Law of Large Groups going Dutch: even when all the people there believe they’ve put in more than their share of the bill, the total falls $100 short.

And, of course, the corollary: the person who counts the money somehow gets stuck covering the shortfall.

In this case, Nic and I split it. But, really, I’m not entirely sure why this always happens. Do people not factor in tax and tip? Do they just suck at math?

Or, perhaps, have they caught on to a cheap living secret I never did? That if you stiff the group a bit, and then pretend you can’t count well enough to collect the dollars, some sucker like me will essentially pick up your first round.