If u have done wudu n glanced at some nude stuff unconsciously, then what u need to do -- a revision of wudu.
What if u have looked at lower part of your body while taking shower or wearing the clothes? Hope u have gotten my point! cuz hopefully u never watch nude stuff while doing wudu :)
None of that actually requires a fresh wudhu. I don't know where this type of thinking comes from. This one brother I knew thought that even hearing a girl's name would require him to make a fresh wudhu. Then another friend would say girls' names to him before the time of salat and he would run off to make wudhu.