Elementary schoolmates would often play jokes on him, but in a good-humored way (everyone except the Satanic always liked GKC).
One day during recess, they stuffed his coat pockets with snow and he didn't notice. When they came back inside, the snow started to melt, causing water to puddle around GKC's desk. A schoolmate raised his hand and said to the teacher:
Please, Sir, I think the laboratory sink must be leaking again. The water is coming through and falling all over Chesterton.
The teacher sent Chesterton to the custodian's office to report the problem. Chesterton, with water streaming from his pockets, went upstairs to the janitor, gave the message, and returned without discovering what had happened.
Schoolmaster Fordham about the Young GKC
"He sat at the back of the room and never distinguished himself. We thought him the most curious thing that ever was. [His schoolfellows noted how he would stride along], apparently muttering poetry, breaking into inane laughter. . .
"I can see him now, very tall and lanky, striding untidily along Kensington High Street, smiling and sometimes scowling as he talked to himself, apparently oblivious to everything he passed; but in reality a far closer observer than most, and one who not only observed but remembered what he had seen."
Maisie Ward, Gilbert Keith Chesterton (Penguin, 1958), p. 27.