I'll say it out loud and proud: I like puns.  I like off-the-cuff silly puns, and well-crafted pun punchlines to a shaggy dog story.  But my favorite kind of pun is the one that is like an optical illusion.  Like the picture that is both a duck and a rabbit, or an old lady and a young lady: your brain tries to hold both interpretations at once – like trying to balance on a narrow rail – but you keep falling off to one side or another.  Or you oscillate back and forth quickly between the two, trying to get the oscillations to go fast enough that they blur into a single understanding of both at the same time.  They never do.  But the attempt mesmerizes my brain.

A whole poem is a bit too complex for that effect to take hold, I think.  But if you read through this once and think "wait, what?" and then you read it through a second time and it makes perfect sense, I feel as if I've achieved my goal.

A worker in fabric's a sewer.
A fast-moving sewer's a flower.
A flower's a plant,
And a woman who can't
Keep her hands off a rake is a hoer.

Based on the suggestion: “sewer” (as in “where the alligators live”)