Teen Titans Vol 2 #5 confirms a theory of mine: Nightwing's costume is made of far weaker material that your average superhero. How else can you explain why all the other Titan's costume's stay in tact while he's suffered severe damage. Risk even gets hit point blank on his chest, and his shirt doesn't have so much as stitch out of place. Whatever the in-universe explanation is, we all know what the real reason: Fanservice! And well love it.