Josh and Danny have gone for a nice day out at the zoo. Or, should that be, a nice, experimental, day out at the zoo? Petty's developed a new SWITCH spray for snakes! And Josh and Danny are willing volunteers. Things start to go a bit wrong though when they fail to SWITCH back into boys, and are spotted by a whole class of girls on a school trip! Luckily, Charlie, an old friend from summer camp, is there to help, and the panic subsides. The trouble is not over yet
though . . .