2. If you encounter a situation described in the question, take out the paper, unfold it. Make sure he/she sees it and gets it.
3. Since USCNCA unique username is VERY easy to remember, if he/she really wants to know you, he/she can easily remember it with a glance of the paper.
4. If he/she really wants to know you, he/she will visit www.USCNCA.com, and easily search out your contact information by using the unique username you showed to him/her .
5. If he/she also wants to know you very much, perhaps he/she will also take out a paper from his/her pocket and unfold it and show it to you in return when you show yours.
6. If he/she actually does not want to know you, nothing happens. You have no regret this time! You did not lose your face in public by trying to talk to somebody who does not want to talk to you.