Usually involves girls in the mens room by the end of the night to make sure the gay male doesn't get molested in the stall while vomiting/passed out in the club.
They are also ment to make the male feel supported or more confident while meeting new guys at clubs.
Their last and more import job is to make sure their male friend goes back from where he came at the end of the night. Not to a random strangers house.
Hens protect their chicks.
Mica: "Oh cool, why, you in the mood to go clubbing for once?"
Gay Male: "Yeah, Mike dumped me so I'm like fuck it, I just wanna hen-up, get smashed and hit the clubs with my girls tonight."