A common type of body modification is meatus (peehole) widening, known as meatotomy in which the meatus is purposely lengthened. This is generally done by the man himself, or non-professional practitioners, without anesthesia.
A complication is that the owner of a widened meatus may have trouble with a dribbling urine stream that is difficult to aim into the toilet. The condition can be surgically reversed.
Your author has imagined that the opposite treatment might be interesting: To purposely partially close the meatus. This might result in a stronger, better aimed urination stream. Furthermore, it might cause longer-lasting, more continuous, more forceful ejaculations. That might be fun. A person could perhaps fake the effect to see what happens with a bit of crazy glue applied to the top or bottom of the meatus. Keep in mind that frequent contact with glue of that sort might cause skin irritation or worse. Alternatively, a couple of closely placed stitches could temporarily reduce the meatus.