Maybe you have a stainless steel refrigerator or a fancy glass door- not sure where this practice originated. One time I photographed a fridge in a junkyard snd the door still had magnets stuck on it!
Some people collect them from places they visit. Send photos if you wish. 
My fridge is covered with magnets!
Have lots of magnets – mainly from travel.
No magnets on my fridge but, I have to admit, I’d cover it with Mary Katherine Gallagher magnets. Love her!
Superstar!
Yes, all sorts!
I only allow magnets on one side of the fridge; and we only use them to post critical info (emergency numbers, recycling schedule, etc.). I can’t handle visual clutter.