I have found poem "For I will consider my Cat Jeoffry" of Christopher Smart (http://www.creekcats.com/pnprice/Jeoffry.html). The first paragraph is the following:
"For I will consider my Cat Jeoffry.
For he is the servant of the Living God duly and daily serving him.
For at the first glance of the glory of God in the East he worships in his way.
For this is done by wreathing his body seven times round with elegant quickness.
For then he leaps up to catch the musk, which is the blessing of God upon his prayer.
For he rolls upon prank to work it in."
What does mean "rolls upon prank"?