Crew risk and boarding drones in FTL's spider event

Why do the guests keep warning about giant alien spiders?

They are referring to an FTL distress-call event where sending a crew member can be lethal and specialized boarding equipment changes the options.

The giant-spider reference comes from FTL: Faster Than Light, where a station's distress call offers a choice between helping and leaving. Sending a crew member can be dangerous, although the speakers disagree over the exact chances of survival and the effects of crew type. A boarding drone provides a specialized alternative to risking a crew member. Its success probability is also briefly disputed before one participant reports that the game's code guarantees success.