look up any word, like fellated:
Everyone knows whales have huge penises, they even make the sea salty with all their semen. A slippery sleeping 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, apparently the 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.
by amnsiac May 15, 2009
Where you use a whale's penis as a sleeping bag.
JD said: "I think I'm going to go for a sleep in my slippery sleeping bag."

He climbed up through the whales japseye and used its penis as a slippery sleeping bag.
by JFromH May 15, 2009