By Clay Shentrup & Warren D. Smith
From Rivest's (1 Oct 2006) paper:
Voters should be cautioned not to casually discard or give away their receipts. (The adversary would be happy to take for free via "dumpster diving" what he might otherwise pay for.)
The receipt could come on two sheets of paper. (Or one, with a very easy way to tear it into two.) It could have half the ballot number on half, other half on other half. Then if anybody discards them, the fraudster and dumpster diver do not know which ballot numbers it really is (unless can paste the right halves to the matching other-halves), and if several receipts went in that dumpster they may have to guess, and guessing is a risky and dangerous thing to do. (Especially since agents provacateurs might just be planting "discarded" ballot halves in the right dumpsters.)
This simple fix seems to reduce the severity of and worry about the dumpster diver attack.