This is a great comic because it shows that you have no idea what the final punchline is going to be. It makes me think this guy should have his urethra for his mouth. He has a mouth for a urethra! Wow, what did I just say? I especially like how the shapes are done in the middle panels with how really everything looks phallic there. The penis this guy has is the least phallic looking thing out there, actually.
I wonder if that body has a penis himself? The facial expressions in this are great too, as it really does seem like someone who would need to go to the bathroom badly would probably act like that. A urethra creature would probably have that epxression too. This is a really good non-sequitor comic and it builds itself well.