Bié bǎi kuòqi le, zánmen jiǎndān chī diǎn jiù xíng.
Stop showing off your wealth — we'll just eat something simple.
Tips
usage
Often slightly disapproving — implies showiness, not just wealth. Pair with 摆 (bǎi) to put on, as in 摆阔气 to show off one's money. The neutral word for wealthy is 富裕 (fùyù).