Im a guy and i like my nipples to stay hard.(and no im not gay as if that has anything to do with this question)and I also got them pierced.They get hardwith normal activities,
but i want them to stay hard all the time.
Can this be done ?
This is NORMAL hormones. I would be more worried if they weren't hard. And you mean under your nipples I assume (Squeeze nipple tip, if that's the hard part, you may just be cold or something else)(for under nipple, push on your nipple, if that part is "knotted", then...)... So, that is normal!
You may (or may not) notice 'breast fluid' coming out of them (especially when squeezed)... That is normal, too.