(n.) (Abrv. PFD) A person who you hone or practice your flirting skills on even though they are already dating or in a relationship with someone else. You usually want to get with them extremely bad, but are forced to resort to playful flirting (especially when the boyfriend or girlfriend is not present).
Can also refer to a person who remains in the dreaded abyss known as the "Friend Zone".
Dude, I would totally get with Sara if she didn't have a boyfriend, but I guess she'll just have to remain my Personal Flirtation Device.
Rachel is so hot, but I'm stuck in the "Friend Zone" so I guess she'll just have to by my Personal Flirtation Device.