Sorcerer in training
More details on the Great Brain entry (since events cover several pages, due to Tom not initially thinking things through). Spoilers for those who haven't read the books.
While Tom was at boarding school, the events of Me and My Little Brain resulted in Tom and John (the narrator's) family adopting a young boy whose family had been brutally murdered, Frankie. This spoiler occurs near the end of the book, so caution highlighting!
When Tom asks the "is there anything new in town?" and makes his bet with John that there is something new in town, Tom points to Frankie. John can't fight back.
But when their mother finds out, ooo boy. She scolds Tom, pointing out Frankie had been in town several times with his previous family.
Tom graciously does all the chores -then heads into town. Their father works at the town newspaper, giving Tom access to all the back issues. (Although he could probably con his way in anyway.) It's the back issues that inform him of the six babies born while Tom was away. (Spoilered because it's spoilered in the trope example; this one isn't a big deal, though.)
Edited by Candi Coming back to where you started is not the same as never leaving. -Terry Pratchett
What's the variant called when the "victim" volunteers themselves for the task without being asked and are genuinely enjoying it? Is it just playing with this trope? Like instead of Tom tricking his friends into painting the fence, in this scenario Tom's friend sees him and without the con setup immediately begs Tom to paint the fence, but it still functions the same way.