Brian looked around the heart, and suddenly found himself being pumped out through an artery. As he was flowing through a vein, a few cells attacked him.
'Uh, can you make it so your cells recognize and don't attack me, Peter?' Brian telepathically asked. Peter made it so, and the attack stopped.
Brian sat down on a red blood cell and rested, deciding to go with it to where ever it took him.
After what seemed like an hour (but really was about half a minute) Brian found himself going through..epididymus?! He stood up on the cell, a little aroused, and very confused. So he jumped off, and saw these little things swimming around him.
'Dude, I'm swimming in your balls!' Brian told Peter.
"What the FUCK?!" Peter said, now in his room at his house. He shrunk Brian down further so he was small enough to ride the sperm. And he did, and told Peter this too.
As soon as he heard this he jacked off. When he finally cummed, he returned brian to his normal size, and he was covered in semen.
"Now i can do a report on the travels of sperm." Brian said, and they both laughed. Peter let him go into the bathroom to shower off.