It is lovely when wordplay works in multiple languages:
Warum laufen Nasen, während Füße riechen?
“Why do noses run while feet smell?”
And you feel a bit of a loss when it doesn’t:
Man braucht scharfe Scheren zum Schafe scheren.
“One needs sharp shears when one shears sheep.”
“Sheep” and “sharp” are not a million miles apart in phonological terms, but they not nearly as close as Schafe and scharfe. In addition, while I’ve translated the German so that the noun and verb are both “shears,” this renders it a bit awkward and not really the sort of awkward that renders it funnier. So perhaps it would be closer to the feel of the original to say: “To spear sharks you need sharp spears?!”