A person in your friend group that you secretly hookup with. You sneak out (usually at night) and do anything from talking, cuddling, making out... to sex (but not always sex). They respect that you want just a hookup friend and you respect them as well. This is not a closed relationship and you expect eachother to hookup with other people- but only if they are not in ur immediate friendgroup. People often use this method as a way to get around ever having to be commited in relationships while still getting some action.
Two Hookup friends sneak away from their friend group for a casual hookup.
1) A friend that you have no feelings for but happen to hookup with. This is usally an agreed upon relationship that is hidden from your other friends. Mostly driven by alcohol but also sober- who deosn't want sober and drunk action?
2) The aftermath of a broken relationship. An ex-couple still wants to have someone to hookup with. No strings attached. Just fun.
Texts after a casual hookup the night before.
Girl: Sorry about last night.
Guy: Don't be. It was fun.
Girl: hahah yeah i guess it was.
Guy: Well then, now that that is settled. Want to come to my room tonight?
Girl: uh.. what would this entail?
Guy: Relax. No strings attached. We can be hookup friends.