Game Imbalances: Cut the Cheese??

[Vitatroll]

What game mechanic makes you salty? The cheese tactics that get you riled up? The thing that makes you say 'not this shit again'?

This isn't a thread about cutting your favorite cheese; the title is just clickbait. Still, it might happen. It might need to happen. Or it might only need a proper counter. The thread is also about stuff with bad cost-per-effect/effort.

So yeah, I'm literally asking people to whine about how [X] is unfair. Expect Billy to be an asshole. These are all opinions, so they're all valid. Even yours, Billy.