Peeled or unpeeled?
Seriously, peeled they won't withstand the pressure and will turn to mush before you penetrate. Unpeeled, cut off the rough tip and COVER IT WITH A CONDOM. There's no real way to sterilize it. Also, don't go farther than halfway, be careful of the curve and go very slowly. I did use one in my youth but really didn't find it all that satisfactory.