I'm going to ask for gas money
Is there a reason you need gas money?
Yes, I am going out of town
Are you taking them with you? I think that it is only okay to ask for gas money if that person is also going with you.
Why does that matter? I'm going to ask for it anyways.
Well, if the person you ask isn't going with you, are you going to return the favor or pay them back later? Because that's just fine too, but don't try to get a free ride.