Be careful what you wish for. You might actually get it

—

No harm in wishing
But, if you go fishing
In deep pools
Where fools
Fish,
Then sooner or later you may attain your wish.

A dainty dish
Not meant for the tasting by such as you
Has led many a man to rue
Their wish
For forbidden fish.

The cat sat on a river bank
Desirous to catch a fish.
Stretching out his paws, he obtained his wish
But, leaning too far over, fell into the water and sank.
‘Tis better to stay on the river bank …