Worse Outcome. Ugly Choice. Hard Bargain. It sounds like three things, but it's actually four. Let me give you a few examples to illustrate this:
We're going to follow Cyril for a bit. He's a bit of an untalented goon with no real skills to speak of, but he's got a knack for being in the right place at the right time and he's got a tongue that's as sharp as a cleaver. One big thing he has going for himself is that he's a Hocus, so he's got his own personal cult of about 15 devotees who worship him, hang on his every word, and follow him around like lost puppy dogs.
A biker gang is moving through the town where Cyril preaches to his flock and before they leave town they've decided to have a little fun. The gang's leader is trying to lasso Cyril with an old plastic rope that looks hand woven. When Cyril tries to escape he's acting under fire and rolls a 9. The MC can offer...
- a worse outcome: Cyril will take 4 harm as he runs into another biker and gets knocked down to the ground, unconscious, but he will get left alone afterward as the gang laughs their asses off in the assumption that he got accidentally killed.
- an ugly choice: Cyril will dive through a window, taking 2 harm, and escape through the back of the building losing sight of the gang and his followers, or get away down an alleyway but drop something important/valuable, like the wrought iron staff that he uses to focus his followers' attention during his sermons.
- a hard bargain: Cyril will get away, but his loyal followers will definitely not avoid the gang's attention.
The gang makes camp in a grassy ravine near town and Cyril, upon learning that 2 of his flock have been kidnapped, decides to sneak into their camp to liberate them. The closest thing to a sneak move in Apocalypse World is acting under fire so that's what Cyril is doing, and he rolls a 9 again. The MC offers...
- a worse outcome: Cyril is caught and captured, but not harmed, by the gang.
- an ugly choice: Cyril was followed by some of his enthusiastic cultists and they get caught but the distraction will allow him to sneak in undetected, or Cyril is spotted by the camp lookout and gets shot, taking 3 harm, but his enthusiastic followers make it into the camp from his distraction.
- a hard bargain: Cyril sneaks in, but his kidnapped followers have been tortured and killed and there's nothing he can do for them now.
Cyril takes the ugly choice this time and tells the MC that his enthusiastic followers get caught. The MC declares them dead, but Cyril is in the camp and his other followers who were kidnapped are there, and relatively unharmed.
The MC declares that the whole gang's encampment is now on high alert, it's going to be pretty tough sneaking out of here so Cyril is going to need to do something tricky to get his kidnapped followers to safety. Cyril is now keenly aware that 4 of his people got killed today and he might get 2 more killed, he's resolved not to let anybody else from his cult die. Cyril frees his followers and instructs them to get out of the camp and back home while he creates a distraction. Cyril runs out of hiding straight for the gang leader with his staff, and declares he wants to use the focusing power of the staff to heel the leader of the gang to Cyril's will. The MC decides that this isn't a manipulation and it doesn't fall under Cyril's normal use of his Hocus powers, she declares that this is another use of acting under fire but Cyril is being inventive and taking a huge risk, she lets him roll his best stat this time, but he still rolls a 9. The MC offers...
- a worse outcome: Cyril is shot, point-blank, by the gang's leader. 5-harm. His followers will get away clean.
- an ugly choice: He creates enough of a distraction that his followers get away, but they've been seen fleeing and he's captured, or he has the full attention of the gang leader but his followers won't leave without him and all eyes in the camp are on Cyril right now.
- a hard bargain: Cyril has the gang's leader under his command, but that doesn't sway the rest of the gang at all.
Regardless of where you're sitting at the table, this is my favorite mechanic. As a player it gives you a brief moment of control, like rolling with a punch or flipping between two choices in a Choose Your Own Adventure novel. As an MC, it offers a challenging moment of looking at ugly/hard/worse options and offering them up as a meal. It is really hard to pull off well as a MC, since a partial success is still fundamentally a success, but I believe that mastering this on-the-spot thinking is what can make or break GMing properly.