Ok, you're mostly all big boys and girls. Everybody know what a friend with benefits is?
What kind of benefits? Have you opened up a joint insurance plan together?
Look it up.
a fuck buddy
or
Friends with benefits (FWB) is an agreement between two people who are both friends and physically attracted to one another to have a sexual relationship. Neither party is considered committed to the other, and both can start dating someone else at any time with no prior warning. A friends with benefits arrangement is not considered dating, a relationship, or even casual dating by most people who use the term.