Bought a pink pair for my 6 year old girl and a blue pair for my 4 year old son to wear to a live gig. They are quite tight fitting so I stretched them over the back of a dining chair for 24 hours or so, and let the kids wear them around the house to get used to them.
At the gig, the kids loved wearing them, their ears were protected, and they looked cool (and parents were deemed appropriately sensible and cool by other gig goers). They did the job brilliantly. Just need some more gigs to go to now.