Someone, something or somewhere which is overpriced, over styled, over rated, or thinks more highly of itself than it deserves.
1. Darling, do you fancy going to that new little Italian place tonight? Nah, it's a bit too poncy for me. I prefer the chip shop.
2. What about the lovely diamond ring there? What? You must be joking, that's far too poncy.
3. Why don't you dress like Mike? Sorry, love, that's just too poncy for my liking.
Often used in the British phrases 'poncing about' or 'poncing around', indicating that a person is acting childishly, dangerously or not being serious about the activity at hand.
Oi leave it out mate, stop poncing around, you could have someone's eye out with that stick.