Everyone knows whales have huge penises, they even make the sea salty with all their semen. A slipperysleeping bag is the act of climbing into a whale's penis, cause you'd totally fit.
"So I saw that Bear Grylls where he slept in a dead camel, apparentlythe desert is cold at night. Weird I know. So anyway, I figured it might work the same with a whale's penis, but I was all wet so I was still cold.
Still though, I'm gonna copyright it, so Bear Grylls can't talk about the Slippery Sleeping Bag without paying out.