I had a friction blister on my penis and popped it without thinking. what should i do to treat it? neosporin?

Vaseline is better: I would avoid activity that would involve more friction with your penis for at least a week. I would recommend applying vaseline or aquaphor ointment daily. Neosporin might be okay, but I have seen many people have an allergic reaction to Neosporin. Also, it's unusual to get a friction blister on the penis. I would recommend having this evaluated by a dermatologist, especially if this recurs.