Comedian Ismo Leikola (@ISMOcomedy) joins Matt and Andy to talk about Finland, language family trees, university physics, snails, LIGO news, a giant Australian meteor, chimps cracking open tortoises, generating power on ships and the fact that Ismo is the first thing that comes up when you do a video search for "ass."

Comedian Michelle Biloon (@biloon) joins Andy and Matt to talk about RFK's assassination, credit card rules, Michelle’s coding past, more cocaine in British sealife, living with MS, how kidney donor chains work and drones delivering organs.

Comedian Tommy Johnagin (@tommyjohnagin) joins Matt and Andy to discuss Last Comic Standing, finding your passion, why farts are funny, Marsquakes, crazy expensive houses, soil damage fueling climate change and a few ships polluting more than millions of cars.  

Zach Reino (@zachreino), actor/writer/host of the improvised musical podcast Off Book, joins Matt and Andy to discuss ancient Chinese medicine’s surprisingly recent history, Germany’s weird Chinese tradition, Arthur C. Clarke’s three laws, reactivating dead pigs’ brains, a brain implant that produces speech, HIV curing a bubble boy, why vitamins from pills don’t work and the Galileo Fallacy.

Comedian Dave Waite (@davewaitecomedy) joins Matt and Andy to talk about khaki diaper butt, geography pride, a black hole image, the video Janna sent about said black hole, world records for rabbit fur and big pizzas, Stonehenge builders, measles and chicken pox and smiling.

Comedian Doug Mellard (@dougmellard) joins Andy and Matt to talk about All Space Considered, asteroid fossils, the Thatcher Effect, upside-down viewing, Tom Cruise's middle tooth, Catalina, earthquake prep podcasts, octopus attacks and octopus wrestling, the rules of kabaddi, eye bees, a four-legged whale fossil, Matt and Andy becoming parasite-famous, a Japanese bomb on an asteroid and India fucking up space.

Writer/comedian friend of the show Nick Doody (@NickDoody) returns to discuss linguistics, space herpes, atoms and the strong force, the reason for zebra stripes or maybe not, a physics theory as to why time flies more as we age, the first female Abel prize winner, famous Norwegians, lady strokes from lady strokes, the Citizens of Nowhere podcast and Bigipedia.

Returning guests Sarah Morgan (@sarahlmorgan) and Brendon Burns (@brendonburns) join Matt and Andy to talk about air travel, SpaceX’s new not-quite-manned flight, monkey peril, the Mars mission that may not be, rare semi-identical twins and a lot of talk about Brendon’s stonefish encounter. Listen to Brendon’s Dumb White Guy podcast and Sarah’s show The Fear.

Cannabis educator Emma Chasen (@echasen) and comedian Marcus Coleman (@MrMarcusColeman) join Matt and Andy for a live show in Portland as part of the Listen Up! festival, discussing the complex science of the effects of cannabis, the difficulties in researching it, and the many hard-to-dispell myths surrounding it.

The final stop of the Probably Science Australia tour brings Andy and Matt to Melbourne on Valentine’s Day, where they welcome Sheree Marris (@shereemarris), author of Kama SEAtra, and returning guest Wil Anderson (@Wil_Anderson) to discuss the sex lives of aquatic creatures, male seahorses who birth thousands of babies, necking sea slugs, barnacle penises, cross-dressing cuttlefish and the fact that the city of of Melbourne was almost called Batmania. This episode is brought to you thanks to the generosity of Inspiring Australia and The Australian Society for Parasitology.