1. Never ask why he/she is seeing no one. It's none of your business.
2. Never ask a single guy/girl whether he/she is gay. Don't be that kind of dog - Snoopy. Don't be rude, period. Besides, it's none of your freakin' business.
3. Never ask his/her age in order to ask (1) and (2).
4. Never ask what is obvious, for Pete's sake. (Who's Pete?) Never assume an effeminate guy or a boyish girl to be homosexual or bi. Do not add to a person's confusion by telling him/her you are confused.
5. Never mention marriage when he/she isn't even seeing anyone. How dare you rub it in?
6. Never scare him/her about growing old and dying lonely and alone. Thanks for your love and care, but singles can manage pretty well. Besides, being married doesn't guarantee you wouldn't grow old and die lonely and alone, either.
7. Never mention children. Thank singles they don't contribute to the population problem.
8. Consider the fact that singleness is as valid a choice as yours.
9. Consider the fact that being single can be a serious religious matter.
10. Rather, ask them why they enjoy being single.
11. Now, prepare to answer the question, Why are you married?
N.B. Did you know that blessed-singleness is the only recognized civil status in heaven? I forgot the Biblical passage. I'll get back to this as soon as I remember.