The substitute biology teacher was there for a mere week, and yet in that short space of time he told us that a) kangaroos have bifurcate penises b) sumo wrestlers can retract their testicles and c) a tribe in Borneo practised contraception by drilling a hole in the bases of their penises, stopping it up with clay, and then when it healed, putting a feather in. When they didn't want to get a Borneo woman pregnant, they would remove the feather. Sometimes I think this man became a substitute teacher just to travel the country telling unlikely penis anecdotes.