Conversation choices that turned out WAY differently from what you expected
TWAU forum seems to focus on the whole 'glass him' choice; people thought they would buy the guy a drink and were shocked when Bigby smashes a glass over his head instead. But TWD had some of these choices, too.
One in Episode 1: when you're talking to Katjaa at Hersel's farm, and she asks 'Don't you wish things could go back to the way they were?', I initially chose 'Things were bad before'; I was hoping Lee would let on that he was going to prison before all this started. In other words, I thought it meant for Lee himself, not as a commentary on the world.
Instead, he went on a hilariously stupid and incoherent digression about how politicians were corrupt or something, which to Lee is apparently not that much different from people being torn apart and eaten by walking corpses. Katjaa was appropriately confused and so was I.
Also, I wanted to tell Vernon politely that I didn't want to leave Clementine with him, given how much the two of us had been through together. But the only option that resembled that was 'Walk away'...at which point Lee turns into a raging psychopath, throwing Vernon up against the door and threatening him with death if he tries to take Clem away. Threw me way off guard.