Catherine Zeta-Jones is out of gift ideas for Michael Douglas after a quarter-century of sharing a birthday … so Michael’s present this year is seeing his wife in her birthday suit!!!

The actress posted a nude as part of a birthday tribute to Michael on social media, joking she didn’t know what else to give him after 25 trips around the sun together.

Catherine, who looks amazing by the way, says the tasteful nude is gift option number two … with golf balls being option one “of course.”

Something tells us Michael’s going to like this better than a box of Titleist … CZJ is wearing nothing but high heels as she peers into a bathroom mirror in her NSFW photo. The shot appears to be a black-and-white version of a color pic originally featured in Allure Magazine in 2010.

On the PG side, Catherine enlisted Bono to help the married couple celebrate their shared birthday … it was a party of three inside their apartment, with the trio singing “Happy Birthday.”

Michael and Catherine blew out a lone candle on a cupcake together … ringing in his 80th and her 55th.