A teen who has autism and a social communication disorder shocked his classmates last week with a moving speech that he delivered at their high school graduation.

Sef Scott, a student Plano Senior High School, began his “unexpected” speech on June 9 by introducing himself, USA Today reported.

"Unexpected. That is what I want you to remember. Unexpected," Scott said. "First and foremost, I would imagine that to the seniors that know who I am that it is entirely unexpected that I would be standing here giving this speech."

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"Let me briefly explain this unexpected choice of speaker. My name is Sef Scott and I am a student with learning differences. To be more specific, I have autism and a social communication disorder," he continued.

The graduating senior explained that he can speak like others but normally did not, before the audience roared in applause. Scott said his brother, a brain tumor survivor, and his mother helped him pen the six-minute speech. He explained his brother gives speeches on his recovery journey.

The teenager made a few lighthearted jokes before delivering his message.

"We all share one thing in common for sure. We all made it," he said "And how do I know that? Well, it's kind of obvious. You're all here with me at a graduation ceremony wearing those caps and gowns. Yes, I have autism, but I am also a smart aleck. Unexpected, right?"

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Scott called on the audience and his classmates to be unexpected, and do something unexpected, which he said could make a person’s day better like thanking the special needs person bagging your groceries.

"You can sprinkle unexpected moments throughout your everyday life that can benefit those around you with very little effort on your part,” he explained.

Scott wrapped up his speech by telling his classmates to follow their dreams and not someone else’s.

"Don't follow someone else's dreams. Don't waste time on something you never wanted. Do the unexpected. It is your life that you are living, not someone else's so do what fulfills you," he said.