It's not that I'm an asshole or anything, it's just that I expect things from people but don't expect to have to do the same in return.
Example (it's pretty stupid):
Someone has a bag of chips and I really want some. I'll ask, and they'll give me some. I'll ask again and they'll give me some more so on until I get pretty much as much as I want. Then I'll have a bag, and won't want to give ANY away. Not one.
Just little things like that, but with many other things. Not just chips.