Short formed of friends with benefits
This entails: two friendly friends who hook up to realease sexual tension as a favour to each other.
This short form is usually used in textual messages, by teenage girls, and lazy people who do not like the sound B makes.
See also, fuck buddy
Pam: Hey Andy, can we hook up some time?
Aaron: Sure, lets get our horny on!
Pam: Awesome, I could really use some friendafits, most deff!
It means having "friends with benefits" such as you can have sex, kiss, hold hands, cuddle and do things that couples do in relationships but you have no emotional attachments. You don't have to care about their feelings being hurt when you are with another person.
Ty: Damn, Tyler and Lianna look like they are together by always holding hands and having sex
Tony: NO, they are just Friend-a-fits.