My dog is very free with herself at the dog park, how do I stop this?

[Little Miss Mary]

My dog is very free with herself at the dog park and it is very embarrassing and I am afraid she is going to get puppies.

I DO NOT have the time to raise a litter of puppies, so I will have to take them to the shelter, and I don't want to do that.

How can I get her to act more like a lady at the dog park?