You've just enjoyed a pleasant dinner with a group of friends or family. Perhaps you had appetizers, certainly entrees, cocktails, dessert... And now the bill arrives. And with the bill arrives that guy. He's been sitting at your table all along, but suddenly he's active, moving quickly to get his hands on that itemized receipt, "splitting" the bill. Just divide it evenly? Oh, heavens no - he wouldn't hear of it. After all, you might have ordered the $16.95 linguine while he had the $16.25 hoagie. Logic would never let him believe that, if you go out often together, that 70 cents would probably come back around.
The bill splitter is often also the bill collector. He figures out what he owes. (which never includes tax and could be shy on a couple of other incidentals ordered) He is also happy to figure out what you owe. (rounding up, of course) By becoming the bill collector, he is able to sort and massage everyone else's money. Funny enough, in the end, he may just end up having to put in less than he originally tallied, because everyone else just paid too darn much. Sorry, waitress, if you get snubbed out of that mediocre tip you were expected.
Once I was at a Mexican restaurant and the bill splitter sauntered in a little later than everyone else, just as a large bowl of delicious cheese dip and accompanying chips arrived. He managed to inhale 3/4 of the offerings. When the bill came, however, he relied on hard facts when figuring his totals - someone else ordered the appetizer, he wasn't even there yet. Hence, it would obviously not in any way go towards his total. I don't like this guy.
*I would like to make an exception to this pet peeve - you did not indulge in alcohol. You're out with a bunch of riotous booze hounds. Don't split the bill evenly.