One of them wants to show me how magnets stick to their arm now. Wish I was making it up
I am sorry, but he is full of s-t, you can tell him that your friend who has PhD in Biology with 20+ year experience in genetics told you so.
However, if his arm is sweaty, a magnet very well might stick, but it is a property of water (high surface tension) and not any "magnetizing".
Superstition squared.