Why do men's nipples get hard?

[Horny-teen]

Why girls do so is it weird

[madhatters4]

per University of Maryland biology dept
"Nipples become erect for many reasons, some of which are not sexual in nature, like if you are cold, or if they get sensation from your clothing rubbing on them. And sometimes a woman’s nipples may not be erect even when she is sexually excited."

[A-Y-Y-Y--L-M-A-O]

mine are hard when im cold so could be that
and how do men's hard nippes make you horny rofl

[cosmo555]

if they are horny or cold

[Bards]

Because they aren't human. So weird.