Did you know I pumped the gas right out of the neighbor's car? The guy is a total loser.
Does your neighbor know you did this? It sounds messed up.
No, I got free gas and he's none the wiser.
If you keep doing this he's bound to find out about it and the relationship between the two of you will sour. You shouldn't do things that will cause you trouble with your neighbors.
Oh, I didn't think about it like that.
It's not too late. Just apologize and maybe buy the guy some gas to make it up. Or if you don't want to do that, you can secretly pump the gas back into his car and stop stealing his gas going forward.