The text is a humorous take on the famous line 'Be vewy quiet, I'm hunting wabbits!' said by the cartoon character Elmer Fudd. It plays on the speech impediment of Elmer Fudd, substituting 'rabbits' with 'runtime errors', which is a play on words for programmers. While it mimics the accent and speech pattern for comedic effect, it does not exploit different meanings of a word or similar-sounding words in the traditional sense of a pun.
Shh ! Be vewy qwiet ! I ' m hunting wuntime ewwows !