Meaning intoxicate & fuck. Used to describe a female whom will engage in sexual intercourse with the person in question after drinking a couple of beers, taking a couple of shots, or smoking some dank marijuana.
The female in question may be dtf after talking to her for a while or having a relationship and gaining her trust but in order to bypass the boring filler on the quest for ass, one would simply suggest drinking with a couple of trusted friends; Especially if the female is unbearably stupid and uninteresting in conversation but has a banging body.
I&F can be classified as easy, all the way to impossible.
Anthony: "Hey Josh, you want to chill with that bitch Ashley and Jessica Friday?"
Josh: "Are they dtf?"
Anthony: "I don't know but they're definite I&Fs
Josh: "This girl Maddy is so fucking stupid. Talking to her's not even worth the pussy."
Anthony: "Dude, she's such a slut. She's an easy I&F"