(Pippin in this story is about 8 in our years, so about 14 in hobbit years)
Pippin had everything planned to perfection. It had taken him a while to work out how to get the bucket up into the tree, the lowest branches of which were a great deal higher than he could reach, but then he had remembered Merry showing him how to tie a rope to hoist it up. He hadn't quite managed to keep all the water in the bucket, but for a young hobbit, he felt it was all going magnificently.
He'd picked his tree well too. It had plenty of large branches, one of which extended right over the road. It would make a superb climbing tree once he was tall enough, Pippin thought gleefully.
Suddenly he heard voices rounding the bend and leapt behind the tree-trunk, rope in hand, breathing in tightly to make sure none of him stuck out. He took a little peek out, just to make sure the voices belonged to his victims, and they did! He felt a giggle boil up inside him and he hurriedly clamped a hand over his mouth to stop it escaping. Cousin Frodo and Cousin Merry would never expect this! They would expect him to be waiting by the gate, bag in hand, eager to spend a week at Bag End (Which he was, but it would be doubly fun if he could trick them first!).
The two hobbits were almost right under the branch. Pippin tugged sharply on the rope and the bucket tipped over, soaking them quite thoroughly.
Pippin leapt back out from behind the tree, giggles finally released, but stopped short when he saw their faces. Frodo looked angry and Merry looked very sad. Pippin stopped laughing and looked at them, undecided as to whether to burst into tears or to simply run away. He hadn't meant to hurt them, it was just a joke. Now he mightn't get his holiday at Bag End. He looked at the floor and waited.
What he definitely didn't expect, however, was exactly what happened next. Cold water was poured right over his head and when he looked up, rubbing the water out of his eyes, Merry and Frodo were stood there, as wet as he was, clutching buckets and laughing uproariously. Pippin took a moment to find words and ended up doing a splendid impression of a fish, which made his cousins laugh even more.
"Oh Pip!" Merry laughed, "I taught you that! You even used my knot on the rope!"
"And I taught it to Merry!" Frodo added, "None of us can claim for the knot though, I'm afraid, it's one of Uncle Bilbo's!"