(Chiefly British, and best appreciated in a British accent.)
Any large-bore corrugated tubing. Generally made of thick plastic - making it stiff - while the corrugations allow for some flexibility. Generally used for routing cables around a room, or exhaust gas from an air conditioning unit.
I say - heat's building up in the machine room. Don't suppose you could toddle over and check the elephant's cock's not fallen off the air con, old boy?