What's worse than finding 10 babies in 10 dumpsters?
Finding 1 baby in 10 dumpsters.
What's worse than finding 10 babies in 10 dumpsters?
Finding 1 baby in 10 dumpsters.
The joke plays on the expectation that finding multiple babies in dumpsters is horrifying, but then subverts it with the idea that finding one baby in multiple dumpsters is worse. This is because it implies a more sinister intent and a much longer search in different locations for the babies. It is the difference between quantity versus the unknown and suspense.