Paul Rudd was promoting Ant-Man on The Late Show With David Letterman last night, which may seem early considering Avengers 2 hasn't even opened yet and Ant-Man doesn't hit theaters until July 17. But, with Letterman set to retire on May 20, this would be Rudd's last time appearing on the show (and, as he reveals later in the interview, he's a literal member of the Dave Letterman Fan Club). It was more of an excuse for Rudd to say goodbye to Letterman and pay his respects before the final show, but Rudd did bring along the first Ant-Man clip and tried his best to explain what this movie is about.

The clip shown is of Rudd as thief Scott Lang, who is breaking into a vault at Hank Pym's laboratory. He expects to find money, jewels or something inside, but all he finds is the Ant-Man suit. Or, as he calls it, an “old motorcycle outfit”.

Rudd talked about telling his son that he was going to be playing a Marvel superhero who answered with, “I can't wait to see how stupid that’ll be.” He had to explain to his son who Ant-Man was and, as you might imagine, Letterman didn't know much about Ant-Man, so he had to explain to him too. Rudd gamely tried his best to describe the Ant-Man character, but struggled to keep a straight face. Just watch him try to explain to Letterman how Ant-Man can also control the ants before eventually giving up and saying, “Well, I guess we all can't wait to see how stupid this will be!” (This is going to be a long press tour if, during his first interview, he already can't describe the concept of Ant-Man without laughing.)

We'll obviously have much more from Ant-Man as the weeks proceed, but this was a fun way to kick off the promotional tour.

Ant-Man opens in theaters on July 17.

Check Out the Full Gallery of Ant-Man Movie Photos