From Dreamwar #3: In the process of trying to get the drop on their opponents, Hal first puts Batman in a giant green BULLET, and then puts the bullet in a giant green GUN -- and FIRES it!
Now, there's plenty of evidence that Hal Jordan doesn't mind using a gun when he has to, but BATMAN?!?! Batman's parents were killed by a gun! Batman HATES guns!
It's doubtful that Hal went with a gun for the purpose of messing with Batman (even though Batman really didn't have a choice in this matter). Hal was probably just being his usual, careless self and didn't even consider the fact that a gun was inappropriate. Still, you can bet this isn't gonna go far in endearing Hal to the Dark Knight.