Looks like the rectum, not hemipene...but yeah, sugar/water paste...keep it on clean paper towels. If it doesn't go down on its own, trip to the vet.
Not something to take lightly, but it doesn't look too severe. I'd probably skip feeding him for a couple weeks as well. Here's a picture of a baby that I produced that had a severe prolapsed rectum(months after leaving my care) that needed to be surgically repaired.
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