But he says the ticket agent told him there was only one seat available and there was a safety issue of being able to put down the arm rests.
"Look, I'm fat. I'll be the first to tell you I'm fat, but I'm not that fat yet where I've got to buy two seats to fly on Southwest, you know what I'm saying? For fat people, there is a bar, and I haven't hit that bar yet. I just buy two, because I just don't like people. I don't like to sit next to people," said Smith in his podcast.
Smith took his seat and was then ordered off the plane. He started sending Tweets on Twitter including one that read, "Look how fat I am on your plane. Quick throw me off."
"They're telling me, 'We can give you a voucher for our Love Program,' and I'm like, love? You just booted me off a plane because I'm too fat, yet I'm not," said Smith.
Southwest Tweeted Smith that they're sorry and issued him a $100 vouchers. In a written statement, the airline said, "As soon as we saw the first Tweet from Mr. Smith, we contacted him personally to apologize for his experience and to address his concerns on both Twitter and with a personal phone call. The policy requires passengers that can not fit safely and comfortably in one seat to purchase an additional seat while traveling. The spirit of this policy is based solely on customer comfort and safety."
Smith replied to the airline's apology with a Tweet we can't repeat, and in his podcast, he said he was treated like a terrorist.
"I kept saying this at the desk, 'Would you tell me, was I violating some FAA regulation?' and they were like, 'No," and I was like, 'Are you sure? Because that seems to be the only reason to eject me off the plane.' There are terrorists that get on planes, and I get asked to get off?" Smith said.
Sunday night, the National Association to Advance Fat Acceptance is calling for a Southwest boycott, urging "people of size seek out and travel airlines that do not have such discriminatory policies."
Melissa MacBride contributed to this report.