The other trick is to make sure you're not the one sitting in the position to hold the check and do the tally - thats a good way to get screwed, too.
I get stuck with that too! - Not sure how to avoid it! - Getting a chuckle though, picturing everyone in a large group desperately trying to look away and look busy or unapproachable when the waiter comes around! I had a friend who, when out at a bar would order a drink and then *disappear* when the waitress came back with it wanting cash on the spot.... At first I thought it was an accident so I would just pay it for her... but it happened too much! So I stopped! You should have seen the look on my friend's face the first time I said "Oh - the waitress came around with your drink, but you weren't here, so she said she'd come back".... She knew she was busted.