Cops and Criminals
Cops are authority figures who carry guns and guns are symbolic of penises. The woman cop is hot because, you know, she's got a gun.
You got caught robbing a bank/doling out some vigilante justice/shoplifting/catburgling and now you've been taken into a private room for interrogation.
Cop: Well, well. You thought you could get away with it but I guess you're in a bit of a pickle now aren't you? You're going away for a long time!
Criminal: I've got something bigger than a pickle right here.
Cop: Maybe we can work something out.
Music suggestion: AC/DC, Night Prowler
Gangster Moll and Mobster
It's sexy because it's dangerous. He's a big man in control of all the organized crime in town. She's in awe of him and kind of afraid at the same time. Girl costume might look like Michelle Pfeiffer in Scarface: lots of make-up and a slinky metallic dress. Male costume might consist of an expensive suit and hat of some kind. Flipside: The gangster is a hot chick like Lucy Liu in Lucky Number Slevin and the moll is a guy who wants to work his way up the mob ladder.
The backroom of the gangster's strip club, which he/she owns because he/she is a gangster.
Gangster: I've had a hahd day! Bubbles screwed up that shipping job and I think he's tawking to the cops. I might have to rub him out, as I do to anyone who crosses me.
Moll: Oh bayby. Let me poah you a drink and give you a massawge. Theah, does that feel bettah?
Mobster: Yeah, but it'd feel even bettah if you were naked.
Music suggestion: Alabama 3, Woke Up This Morning
Hooker and Client
For reasons beyond my comprehension, paying for sex is still considered taboo, risqué, and dirty. So, it's titillating. The "hooker" gets to feel dirty for being a hooker and "the client" gets to feel dirty for hiring the "hooker." And feeling dirty means good sex. Remember, no kissing on the mouth.
A hotel room
Hooker: So, what can I do for you?
Client: I've never done this before...
Hooker: That's OK sweetie. Just tell me what you want me to do.
Client: Well, I've always had this fantasy about a sexy school girl...
Hooker: That'll be a hundred bucks extra. Just let me get my costume...Teacher! I can't believe I failed the test! I really need to pass this course. Isn't there anything I can do?
Music suggestion: Prince, Darling Nikki
Use your imagination. What character do you dream of being/doing? Scenes can be as complex and involved as you like. Hell, you can even write scripts and make scenery!
As long as you stay safe and respectful of one another anything should go.