Consider the hagfish, at length if you think you're hard enough. Choice hagfish tidbits:

Typically, a hagfish will release less than a teaspoon of gunk from the 100 or so slime glands that line its flanks. And in less than half a second, that little amount will expand by 10,000 times—enough to fill a sizable bucket.

You could inject a hagfish with an extra 40 percent of its body volume without stretching the skin.

The entire hagfish is effectively a large gut, and even that is understating matters: Their skin is actually more efficient at absorbing nutrients than their own intestines.

[Last but not least, a photo caption:] A car is covered in hagfish, and slime, after an accident on Highway 101.