FB users - when someone names you in a FB challenge do you respond?

I will never share because someone tells me they know only 3% of their friends will share. I don’t respond to emotional blackmail. But this is different. Say someone tags you in a photo or book challenge like post the covers of books you like for 25 days with no explanation. I don’t want to do them either. Do I owe the person who tags me an explanation or can I just ignore it?

This question is in General and should be answered by Facebook users only. I don’t want to hear from people who don’t use and can’t stand Facebook. Those will be flagged (and possibly flagellated.)