Agreed to do MIL's makeup on my wedding day and sort of wish I hadn't...

[Meta4]

She caught me offguard earlier and asked if I'd make her up on the day in a couple of weeks' time. I agreed because I find it hard to say no... However I now feel a bit panicked at the prospect of adding something else to the morning's agenda...

How can I politely back out?! (And wedding is very low-key - there's no one else going she could ask.) Should I just shut up and do it?!

You could tell her you're nervous about messing it up especially if time runs out and suggest you both go to a dept store and her have a makeover e.g. Bobbi Brown is good. If you're both paying attention to what the assistant does then she can do it herself if needed. I did this when I was a bridesmaid, and my friend did it herself with me around to help if needed.