An "IP Checkpoint" is when the woman you're about have sex with whips around, reveals themselves to in fact be a man, and shoots a load in your face. The term was coined as a nod to the well-known fact that many Iraqi Police are corrupt and likely to betray you.
John: "So I wanted to go munting last night but got back too late, so I went down to the CAC to chill and met this fine looking woman. We started talking and then she invited me back to her room. So we head back to her room, she turns down the lights, we're making out, her chin's a little scratchy but you know how some women are, things are going great and she tells me she wants me to take her from behind and I'm thinking to myself "whoa, straight to anal, that's something" but I'm up for it. So she puts her hands up on the window and sticks her ass out and I'm thinking "Damn, too bad E isn't here or we could have a David Copperfield" and then she suddenly whips around and blasts me in the face with a load of baby batter!Dude pulled an IP checkpoint! I haven't been that suprised since that Spiderwoman last week. I guess I should have stuck to my plans and gone munting."