Seinfeld and Alexander were seen outside Tom's Restaurant in Manhattan this month, but neither actor has said publicly why they went to eatery, which served as the facade for their characters' favorite coffee shop on the iconic sitcom.
CBS quoted Seinfeld as saying on the WFAN radio program Thursday they weren't filming a commercial or an episode of his new show, "Comedians in Cars Getting Coffee."
It's "not not those things, either. It's a secret project," Seinfeld said.
"I gave you more now than I've given anyone," he added. "I told you what it isn't. And then I also told you that it isn't not that, either."
He went on to say the meeting -- whatever it was for -- was filmed and the finished product is in "short-ish form."
Asked if other "Seinfeld" characters were involved, Seinfeld replied, "Yes, there were."