I was getting onto the tollway, trying to merge, and the traffic just wasn't giving me an opening. Rather than come to a complete halt and lose all hope of ever merging in, since the merge area at that on-ramp is particularly long and is more of a "lane ends" situation than a normal on-ramp merge, I kept my speed up. Ended up passing a few cars as their lane slowed down a bit. (Including a British LTI cab painted in the colors of a local taxi company, except instead of advertising their route as "[suburb] to O'Hare", it was written as "London to O'Hare.")
I found an opening I could fit in and started merging in, at which point the driver who would've ended up immediately behind me sped up to close the gap and leaned on her horn. I almost made it into the lane before the front corner of her car passed the rear corner of mine, but not quite. I was rapidly running out of lane, and had my front corner in front of her, but if I fully merged in, I'd hit her, so I had to yield--at which point I ran out of road and ended up on the shoulder as she passed me, glaring daggers of deadly death at me and doing her best to tailgate the guy in front of her so that there was absolutely no chance that anyone would have room to get in front of her.
Needless to say, this put a bit of a dent in my normally sunny disposition and I had a few choice epithets to throw in her general direction.
A driver a car or two back was kind enough to let me in at that point. I ended up following the cranky driver onto the tollway that forms the next leg of my trip home, and had the pleasure of managing to change lanes to get into a faster-moving one from the slower-moving one the exit ramp turns into before she could, and then have her merge into the lane right behind me. That was short-lived, however, as she quickly cut across three lanes of traffic in a construction zone and looked like she might've cut off at least one other driver in the process, just so she could wedge herself into the "fast" lane (which isn't very fast there, due to the construction, but I digress). I lost track of her in traffic shortly after that, but I thought I later saw her trying to merge onto busy traffic coming on and off an off-ramp at a cloverleaf and not having much luck until someone let her in.
I normally have to be a defensive driver because of my deficiencies in depth perception, but times like this serves to make me that much more of a believer in the Truth of something I read a while ago in an article about the active aggressiveness of many Chicago drivers: (paraphrased) "Signaling lane changes in advance of starting move over is taken as a sign of weakness and thus as an invitation to block you out of your desired lane."
Feudalism: Serf & Turf