We use the kitty method when we go on trips. Everyone will throw in $20 or $50 in the ashtray. When we fill up with gas, get ice, etc., the money comes out of the kitty. Every one takes care of their own food and beer. When the kitty is dry, we "all" fill it back up again. If we have a flat tire, money comes out of the kitty to repair it. If there is $20 left at the end of the trip, we tell the guy to change his oil, and wash his car. When you do it this way, no one feels like they are getting screwed.

If your "friends" aren't willing to share expenses, find new ones, because they aren't worth having. You shouldn't have any problem finding guys willing to pay their "fair" share. Hate to say it, but I have to agree with your wife. When it comes to your friends, it's time for a change of scenery. If not, go on a trip with them, and keep your wallet in your pocket, and see how they like it.
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The best way to be succesful in life is to keep the people who hate you away from the people who are undecided