our gymnastics gym does 'parent night out' nights as fundraisers for the cheer teams' travels - and our Y does them too ... each parent pays $25 - 35 (depending on the place) for about 3 hours - kids come to the gym/Y and play/eat pizza/watch a movie while parents have a night out.
and both our gym and Y do them 2 times/month and they are usually close to selling out