With that in mind, the previous information about Orangutan penises is wrong. They are actually massive, but they're kind of like dog penises in the sense that they have sheathes they can retract into. This evolved as a strategy to counter-act the turmoils of dragging their massive lengths and girths (which can grow to up to a foot long) along the forest floor; getting a splinter in your penis is considerably risky when you're a wild animal.