I've worked at a Lowes, I said everything I have always want to.
The main ones were...
"This is America, I don't speak Spanish, so if you have a question learn English." The guy then followed me for 5 minutes before I had to go "Get the hint!"
One woman was being a pain, so I turned around, a foot away from her and called her a bitch and walked away.
Once and awhile I couldn't help someone and they would ask for a manager and my reply would be something like "I'd like to see one too, if you find one tell them I say hi".
A favorite of ours, someone was written up for once, was when someone asked "Where is the ______?" The number one answer, "Home Depot".
I didn't really fight or argue with coworkers that often, we just shared stories of how much we hate costumers and the no show managers.
The only thing I have ever held back on was going "Fuck off" to two of my managers (I had about 15). That place was a living hell, it's retail, but it's the hell of retail. Contractors ask you how to build things, really scary. Even my last day there I didn't tell my asshole boss to fuck himself. If I ever see him again I will, what a fucking lazy jackass.