Billy was a sperm. A big sperm, as sperm go. This was because he wanted 
to be the one that fertilised that egg when the time came. So he was 
always working out, training to be the best. All the other sperm laughed 
at him, but he said: "Just wait. I'll prove you all wrong."
 One day, all the sperm felt themselves getting hotter and hotter, and 
they knew it was time. Off they swam, and before long Billy was way out 
in front of the rest. "Bloody Hell," they said, "Maybe he was right after 
all,". Then, they suddenly saw Billy swimming back very quickly. "What's 
wrong?" they asked. "Get back!" puffed Billy. "Get back- it's a 
blow-job!!"