OK, here's something a bit experimental. I took the same picture, and captioned it 5 different ways. Each caption tells a different piece of the same story. The question is: which stage of the story is the sexiest? Pick your favorite picture...this will indicate which stage of the ballbusting process you find most erotic.
(BTW, the basic story is: A girl complains that her roommate doesn't clean up enough, so he proposes to have a wrestling match, and the loser will do all chores for a month. She ups the ante by suggesting they wrestle naked, and the loser will have to stay naked when in the house for a full month. He agrees, thinking his wrestling experience will easily beat her, but she grabs his balls and the rest is history...)