Could it be a vent for plumbing. Seems to me I saw water coming out of the same spot on a fifth wheel in a campground when the owner accidentally hooked up his water to his plumbing tank flush. He clearly was a newbie. We just happened to be walking by and saw the water pouring out of the front of his rv. We shut off the water at the hose bib and knocked on his door. About the same time his wife started yelling from the bathroom lol. Guess maybe the toilet was full or overflowing. Im sure he did some damage.