The same way you make a guy's nipples hard.
Impossible
Flick them very hard You will jizz...............every where
To make your nipples hard, you need to sexually stimulate yourself. Massage your boobs, rub them, squeeze them, etc. Also, flick, lick, and touch your nipples as much as possible. Your nipples will get hard once you're horny and sexually stimulated.
Maybe if used externally.
Most guys do.
If you want to make her nipples hard play with them use the tip of your tongue around her orioles or a piece of ice and for sure they'll get hard
Play hard to get.
I'm in your boat too and I hope you get an answer
Nipples that are really hard are referred to as being taut. They can also be called stiff or hard.
Some do.
the pervs of the world find woman nipples sexual but not men.