Stan Lee let it slip that he will have a very different cameo in 'X-Men: Apocalypse'

Stan Lee will have a cameo in "X-Men: Apocalypse" that is "different than every other one I've done," the comic book legend revealed at Comic-Con on Saturday.

During an "Ask Me Anything"-inspired panel, a fan asked Lee what his favorite cameo was.

The Marvel legend has appeared in more than 20 cinematic adaptations of his comic books - between the 1989 made-for-TV movie "The Trial of the Incredible Hulk" and this year's "Avengers: Age of Ultron."

"I really love them all," Lee said, before admitting that his next cameo is possibly his favorite.

"I did a cameo for the next 'X-Men' movie," said Lee before stopping short. The moderator whispered in his ear, assumedly, that the topic was off-limits. He claimed Marvel employees in the audience were giving him dagger eyes.

"When you say I'm not allowed - will I be arrested?" Lee quipped.

Fans cheered, egging him on.

"When you go see the next 'X-Men' movie when it comes out, and see my fantastic cameo, you will say, 'I remember he told me about it here," Lee said. "It's a different cameo in that it has one additional thing in it."

Despite the ambiguity of Lee's statement, the crowd went nuts.

"And if that doesn't make you go see 'X-Men,' I'm wasting my time," he added.

Fans will have a while to wait a little while.

"X-Men: Apocalypse" hits theaters May 2016.