Having doggy-style sex with your girl on the bed. With her ass is in the air and her face on the matress, you give it to her so hard, that her head ends-up sliding under the pillows. Once her head is burried, shove your thumb in her ass and scream "Polk-A-Roo!!!" ...and sure enough her head will appear from below the pillows.
After a good night of drinking with my girl, I took her back to her place and gave her the Polk-A-Roo!