Then smear it on there and pretend it's glue. It works great.
http://en.wikipedia.org/wiki/Wheat_pasting gives more tasty details.
The story behind the picture:
To drive from Boston to Florida without falling asleep and dying, I checked out five gallons of books-on-tape from the Cambridge Public Library to listen to on the way. When I got there alive and finished the tapes, I put them in this box to mail them back. My sister didn't have any glue to put the address label on, but my brother-in-law had just cooked up a mean batch of pasta. I mashed up a couple of noodles to use as glue, and sure enough, it worked like a charm.