You are fucking your woman. Your cock is in her, and your hands are touching the bed (preferably the headboard if there is one), but every other part of your body is "in the air" (not touching anything). Thrusting is often assisted by pulling and pushing on the headboard.
Just before I cum, I like to employ the flying fuck maneuver and ream Sarah's pussy.
People who are connected to each other via the transmission of an STD.
BOB: Jane is such a fox!
JOE: Yeah, the sad part is, we are part of the same STD chain, but, I have never actually fucked her.
JOE: Jane gave herpes to Kate, that ugly bi chick I fucked last summer when I was waisted, and Kate gave me herpes. So Jane and I are in the same STD chain.
BOB: Oh, I get it! Cool.