Gurgle Gut is a pranking elixir mentioned in the Keefe's Short Story, on Keefe's first day on bed rest. After he had slipped Ro a hush slush, he believes that she may have put this elixir into his breakfast. Through this it is also seen that Keefe is familiar with the solution, or at least it's effects, that are described to make the victim queasy. In the case he was right about Ro pranking him back with this, they apparently would both equally suffer when the gurgles broke free.
In Keefe's detention record in Unlocked, it was mentioned that Keefe had once slipped this into Fitz's food as a prank. Though Fitz brushed it off as a joke, that didn't save Keefe from punishment.