Perhaps this is just one of those "guy things," but does anyone else trade off money for beers and drinks all the time?  Or do my friends and I need to get some professional help?

We were just emailing back and forth about our trip to Philly and I made the majority of the reservations with my credit card, and while telling the guys what they owed me, I rounded it off to a lower, even, number and said "you can just buy me a beer this weekend."   I think its a male ritual or something, or do women do it too??