This page lists every time Needle slapped someone, and the reasoning behind it. Almost everyone was slapped for referring to Needle as "Needy".
In Power of Three, Announcer was listing the members on Needle's team, but when he reached Needle's, he called her "Needy" instead. She slapped him.
In Puzzling Mysteries, the same thing happened. This time, Needle slapped the Announcer so hard that he needed up in the Cake at Stake arena.
Later, Announcer used her as bait to slap Coiny away, calling her "Needy", then while she is leaping at him, quickly gets out of her way. She accidentally slapped Coiny.
When getting to Needle's votes in Cake at Stake, Announcer said "Needy" and was slapped by her. When Needle is learnt of her elimination, the Announcer held a small flashback to all the times Needle was called "Needy".
In Insectophobe's Nightmare, Announcer referred to Needle as "Needy" and was slapped.
In Gardening Hero, when calling the eliminated characters that have a chance to rejoin the game, he referred to Needle as "Needy", and was slapped by her. To irritate Needle even further, he called her "Needy" another three times, and was slapped by her again in those three times.
In Puzzling Mysteries, Coiny wanted some silence at Cake at Stake, cutting the Announcer off whenever he talks. Annoyed, he said "Needy". Needle leaped in for the slap, but Annoincer moved out of her way and she accidentally slapped Coiny away.
In, Half a Loaf Is Better Than None, Coiny asked Needle if she knows how to get out of the bread basket, once again calling her "Needy". Needle slapped him.
In Zeeky Boogy Doog, Coiny was between Pin and Needle. He commented that he was surrounded by "pins" and "needles". Needle slapped him. Coiny was angered by this, saying that he didn't even call her Needy. Needle slapped him again.
In No More Snow!, Coiny called for Needle, saying that he has a way to get out of the canyon, but referred to her as "Needy". He was slapped.
In Welcome Back, before Tennis Ball and Golf Ball goes inside the Science Museum, Needle approach them, asking them not to. Golf Ball asked why, and called her "Needy". She was slapped. Angered, Golf Ball tells Needy to slap some strangers that had probably called her "Needy", and was slapped again.
In Rescission, Bubble said that their alliance is too small, after Pencil's elimination, and asked Ice Cube what should they do. Ice Cube commented "Needy has got to join!" and was slapped by Needle from the TLC.
Later in the episode, Leafy asked how did Needle's yeast cake has grown so big to the point where it has become a planet. Leafy commented to Needle that it's "pretty big, Needy" and was slapped.
In Bridge Crossing, Leafy is once again talking about Needle's cake, and again accidentally called her Needy and was slapped. Leafy tried to calm Needle down, but was slapped for calling her Needy again. Angered, Leafy asked "Needy" if she wanted a fight, and was slapped again. Leafy snapped, and slaps Needle back, to the point where she is blown away.
In Get Digging, while Needle was collecting yoyleberries, Leafy teleported in front of her, and said that she's thankful for not being too needy. Though she wasn't referring to Needle, Leafy was slapped anyways.
In Bridge Crossing, when Bubble was popped by Needle, she was disgusted by Match. Pencil begged to differ, and said that she "love Needys". Needle slapped her, and Pencil angrily replied that she said Needle.
In Insectophobe's Nightmare 3, Pin said to Needle that they are the only two that survived the poisoning caused by the spiders, calling her "Needy". She was slapped.
In No More Snow, Coiny's plan to get out of the canyon was to call Needle "Needy", than have her slaps them out of it. Yellow Face called her "Needy", and was slapped away from the chasm. But Needle is still stuck, due to the fact she can't slap herself up. Yellow Face said that they must get Needy up, and Needle tried to slap him, but failed, because she was stuck.