What would you do if you learned a friend crushed on you?

If the friend doesn't know that you know, there's no need to do anything.
If the friend told you, they're taking a risk....I'd let them know that I don't have a problem with that but that I don't feel the same. That shouldn't upset them....but sometimes it does for some reason.

Explain to them that I appreciate the feelings, if it is mutual then great, but if not ill be honest with them to prevent any hurt feelings - hopefully.

I would be honest witn them

I make it clear that I have my man and I'm not interested in anyone else - works well online and in real life.

That happened many years ago. I was honest with her, and we are still friends after all these years.

Tell them how I feel but also let them know how important their friendship is to me.

We were young but I had that happen. It was awkward for a bit but it got better

distance myself ,ghost them lol

I had this happen. She ended up hating me.

Crush them back ffs!