From the Beatles:

"If you drive a car-car I'll tax the street
If you try to sit-sit I'll tax your seat
If you get too cold I'll tax the heat
If you take a walk I'll tax your feet"

And from Denmark via Reuters and the (highly recommended) TaxFoundation blog:

"Denmark, with the world's highest income tax levels, wants sperm donors to pay tax on the 500 crown (46 pounds) reimbursement men receive for their services."

Andrew Chamberlain of the TF rightly notes:

"However, the story isn't what it seems. It turns out that until recently fees earned by sperm donors have been tax exempt. So the so-called "sperm tax" is in fact the removal of a distortionary tax preference from the Danish tax code. For better or worse, that's usually good tax policy since it simplifies tax rules and treats income from different sources more equally."