Hi Daniel,
 
	Yes, the walls of the anal canal and colon are thin and will absorb the semen. You probably will not need a plug but have some seepage in your underwear. A partner with a very long cock with shoot his baby batter deep into your colon and you may not have seepage.  A woman's vagina has much thicker walls so semen will not be absorbed and will reach their target destination, an egg in the uterus.  Here is an interesting German video I came across.  Almost scientific!
 
	
	shemale anatomy - XVIDEOS.COM.mp4