Okay, so you find that ONE chick in the strip club that you wanna see after hours and you don't know how to do it... Here are a few ways that have worked for me. Keep in mind this is for giving donations for their time, not just out on a date.
1. "I have a hotel room near here, not sure if you ever meet customers after hours"
2. "I feel like shit for asking this but do you ever see customers after hours"
3. "I know you probably don't but do any of the girls here see customers after hours"
Number 3 is my favorite and most reliable. It says to them that I am not threatening but interested. If they do they will let you know usually, and if they don't they are usually pretty cool about it.
Another tip is to go to strip club review sites and look around. You'll see somethings said in code there.