Lunchtime conversation

Almost every day, I eat lunch with a group of coworkers, and we generally have entertaining conversation, often about diarrhea and Canada. Today, we started out by talking about a recent scientific article about a contagious tumor in dogs. Yeah, nerd stuff. Then, it became a language discussion about the word "bitch," in which we decided that everyone aside from dog breeders who uses the term bitch to refer to a female dog is not doing so seriously. We decided that it would be funny to start using bitch in conversation and set up a weekend challenge: You must go up to a stranger who is walking a dog and use the word bitch. As in, "What a cute little bitch!" or "Is your dog a male or a bitch?" or "Can I pet your bitch?"

The last example led to a new level of the challenge- anyone who does the following automatically wins:
A man and a woman are walking a dog. The man is holding the dog's leash. You ask the man "Can I pet your bitch?" and then start petting the woman.

We classified that as Level 3 in terms of potential offensiveness. But still, funny as hell. A few minutes later, someone came up with a Level 4, and it starts like this:
A man and a woman are walking a dog and a cat.

I'll let you come up with your own ending.