The The Chimp Who Loved Me looks pretty good:
"I started to undress by the shower door. Then I felt eyes on me. Sammy was watching me from the doorway. Hmm. Odd, but not threatening. I stepped into the shower and turned the hot water on. Chimps do not like water, so I figured I was safe, and I needed a little breather from carrying him all the time. Suddenly, I noticed my chimp child was gone, along with all the clothes and towels I had laid down on the floor. Suddenly, Sammy came full speed around the corner, hooting and grinning, and launched himself at me! Fully Erect Sammy! "
Via Dan Lyke.