Danny is a character is the Ramona Quimby series.
He first appears in Ramona Quimby, Age 8 and then again in Ramona's World. He starts off as looking like a boy 'whose father would take him to ball games,' as described by Ramona, because he was wearing a shirt that read, "Earthquakes", which Ramona decided were some kind of team. Danny steals Ramona's first-day-of-school eraser and is seen throwing it around with around boy. Ramona calls them 'yucky yard apes', which was how Yard Ape got his nickname. He later gives the eraser back. While doing so, he calls Ramona "Bigfoot" due to her slightly oversized shoes, and she corrects him, saying to make that Superfoot.
Later in the book, Ramona cracks an egg over her head and has to go to the office to wash her hair. Yard Ape comes to collect her and bring her back to class. This is when Ramona begins to have a crush on Yard Ape, due to finding it flattering that he called her "egghead" (which, unbeknown to him, means an intellectual).
Some time later, Ramona and Danny sit next to each other on the bus and he calls her "egghead" again, and she plans to tell him to call her "Deviled Egghead" instead, but due to feeling out of sorts, she can't be bothered. When it turns out that her uneasiness was due to stomach flu and her class makes her "get well" cards, his threatens to eat her eraser and calls her Superfoot again. She is not offended, but instead glad that he wrote something original.
In Ramona's World, Yard Ape drops a note on Ramona's desk during class and this mysterious note was snatched by the teacher before Ramona had the chance to read it. Since then Danny avoided Ramona for a while. In February everybody in the class has to give each other Valentines, so Ramona gives Yard Ape her school picture of her making an ugly face. In return, Yard Ape gives her an original poem: "If you are eating peas, think of me before you sneeze. From: Yard Ape, President". Ramona leaves the classroom happily because the poem shows he likes her.
Yard Ape also features in the TV series -- in "Squeakerfoot", he teases his classmates by wearing an ugly mask and pretending he's a mad scientist. Ramona is not scared and calls him "Yard Ape" due to seeing him as "a big ape that chases you around the playground". He calls her "Bigfoot" like in the book due to her shoes, but she tells him not to and later tells him to call her Squeakerfoot instead. Later, in "Ramona the Patient", he again sends her a get-well card that she finds amusing.