I'm gonna go with "racing games" as well. I can't remember the specific entry from the "Need for Speed" series that I'm thinking of, but the AI cheated so badly and obviously that I've never touched another NFS since. It might have been Underground or Most Wanted, not sure. I remember having the AI crash headfirst into a wall and be behind me again within seconds despite my flawless high speed manoeuvres. Or when you drive 5 laps out of 6 flawlessly, then clip your wing mirror on an obstacle, causing you to slow down by 1mph and every AI overtakes you.
You can't lap them, accidents don't slow them down, it doesn't matter how much you upgrade your car or how well you drive, they will always be a few meters behind you and overtake the instant you drive anything less than perfectly. F**k that s**t.
Mario Kart 8 on the Wii also annoyed me. I did most of the races in most classes, but there were a couple where no matter how well I played, I could be out in first for ages, then you get rocketed, shelled, flattened, knocked off and sent to last. F**k you Mario Kart.
I kinda want to mentioned Dark Souls 2 that i'm playing atm. NG+ in particular is a step up in difficulty. Now I'm not complaining about the difficulty of a souls game, but every so often it veers from "tough but fair" into downright cheap territory. I don't like it but don't mind dying to my own misstep or misjudgement or from being outplayed. But then you get enemies that just avoid everything you throw at them, have infinite stamina and hit for 2000 out of my 2200 HP pool. GRRRR.