The Crazy, Stupid, Love star braved the wet weather and returned to school in New Jersey, where he addressed graduates, including his niece Maggie, on Class Day.
Keeping a straight face, he said, "You are young. And because you are young you are wrong."
During his 15-minute keynote speech, Carell admitted that his college experience was far removed from the technology-filled world of today: "If we didn't know something, we didn't Google it. We just made an educated guess, or we made it up. And if you weren't right, you could leave before anyone had time to check your facts."
The funnyman also got serious for a brief moment as he offered up a genuine piece of advice.
He told the crowd, "Show up on time, because to be late is to show disrespect. Get a dog because cats are lame. And every once in awhile, do something positive in the world."