[nitrogen]

x. I think it makes him sound childish rather than intense.

The definition of what sounds childish and what sounds intense is largely cultural and situational. When you realize that all words are just words, and it's people that ascribe meaning to them, you and your social group can mutually decide exactly what meaning you want to assign to each word.

What makes some words special? Why is it not okay to say some words, but okay to say fun? Truck? Luck? Ship? Brit? Shiitake? Shih Tzu? Witch? Bishop? Custard? Bass? Crass? Aspect? Would you be offended if you heard someone say merde but didn't know what it meant?