Two jobs ago, I thought I had a good relationship with the company I worked for, but I didn't really get along with the new guy they'd hired to be a project manager. As an example, I spent all afternoon one day explaining to him that database normalization was standard "best practices" for something like 30 or 40 years--this dumbass wanted to de-normalize the databases so that we had duplicate raw text across all of the tables. Worse yet, he wanted to combine all of our specialized table structures (names, addresses, document information, etc) into one single giant database table. Which means we'd have had TONS of duplicate data in the database, which is a recipe for absolute disaster and which totally breaks the whole "relational" part of "relational database". It was clear the guy never really worked with computers except maybe from a management standpoint. Anyway, we butted heads a few times, but it was never openly hostile.
So, when I gave him my verbal two weeks notice, he asked me to leave immediately. So I guess he didn't like me just as much as I didn't like him...probably for making him look dumb in corporate meetings.
A half hour later he came back to my office and asked me why I wasn't gone yet, and I told him I was crafting my resignation letter, and followed it up with "And I'll probably still be here for another hour working on it..unless you plan on having security throw me out."--basically daring him to do just that. He declined, naturally.
Two days later he called me sounding desperate and asked me for the passwords for my computer and for the source code repository (which he should have had already, but evidently a couple of other key people left the job recently as well). I snorted on the phone and said "well, you know, if you'd have let me work out those two weeks, you could have just came by my desk today and I'd have been glad to help you out. As it is, my consulting rate is $75.00 hour..."
I think those are the only two times I've ever really been obnoxious leaving a job, and I feel pretty justified in both of them.