No, the “Demon” core incidents - there were actually two - had nothing to do with a “prank”. It was a field expedient way around established precautions.
Slotin in particular was well known to be complacent, a bit reckless and not a strict adherent to nuclear safety or established procedure, and it killed him.
“Tickling the dragon” was yet another procedure entirely. It was a bit insane but they knew what they were doing.
According to Richard Feynman in his book “Surely You’re Joking, Mr. Feynman”, this was indeed something people did as a prank.
I didn’t mention the “Demon” core incidents and I did specify Slotin was demonstrating the process to people and bypassed the safety precautions.
“Tickling The Dragon” was the “prank” I was referring to, but Slotkin was doing the equivalent of “tickling the dragon” by bypassing the safety procedures, even if he wasn’t doing it as a prank.