Hypothetical situation:
A dear friend or family member comes to you and asks you to co-sign for their loan. Let's say the reason they need the money is not a life-or-death type of situation. Perhaps they need something (a car, to get to a job) or want something (a kitchen renovation) – but we're not talking about a serious medical or other "emergency" issue. (I think co-signing then is a separate question.)
Anyway, let's say you'd rather not co-sign, since you know how co-signing for a loan can lead to problems for you down the road. (Refer to this question, and this question.)
What are some ways you could politely – but effectively – reject a friend or family member's request for you to co-sign for their loan?