I was on a bus last week, contemplating the smudges on the window and otherwise minding my own business, when I ran straight into Jesus. He was wandering around the front of the bus, muttering to himself, dressed in a surgical scrub top with a blue and green sarong wrapped around his legs.

Now, I know what you’re thinking. Jesus doesn’t wear surgical scrubs or a sarong. The real Jesus has flowing white robes and a majestic golden halo — and he always holds one hand slightly aloft as if he’s perpetually flagging down a waitress.

Well, this Jesus didn’t have any of these things, so even I was skeptical of him. He looked and acted like a man with serious mental or emotional problems. In fact, I thought he was a kook, at first.

“I’m … I need to see a doctor,” he was muttering. “I don’t feel very good. I need to see a doctor, please.”

The bus driver kept one eye on the road and one eye on the kook.

“Hey, man,” the driver said with conciliation, “Why don’t you sit down, take it easy, huh? We’ll get it fixed up in a bit.”

The kook looked around as if he were lost, then nodded and surveyed the bus. I didn’t avoid eye contact, but I didn’t go out of my way to make it, either. Did he need help? Was he a sociopath? It was hard to tell.

He shuffled down the aisle and sat down in the empty seat across the aisle from me.

Great.

“Badda-bing, badda-boom,” the kook babbled to himself, starting straight ahead. “The bus goes. The bus stops. Doors open. People disembark. The bus starts again. Vroom.”

He reminded me of Dustin Hoffman in “Rainman.” I tried to remember what condition his character had: Was it Parkinson’s?

“Badda-bing, badda-boom,” the kook said matter-of-factly, still staring straight ahead. “The bus stops, the doors open. Badda-bing, badda-boom.”

Autism, I remembered. It was definitely autism. Definitely.

“Are you from San Francisco?” the kook asked. He was looking straight at me.

I was unnerved by how close his guess was.

“San Jose,” I said.

“Where’s that?”

“It’s about 30 miles south of San Francisco.”

“Do you like baseball?” he asked.

“I guess so,” I said. “Why do you ask?”

“I like baseball,” the kook said. “I knew a baseball player once. His name was Ted Williams. You ever hear of Ted Williams?”

“Honestly, I don’t know that much,” I said. “I played ball when I was a kid, but that’s about it.”

“You ever see ‘Taxi Driver’? You know, De Niro?”

I shook my head, and Jesus became confrontational.

“You talkin’ to me?” he demanded. “You talkin’ to me? I don’t see no one else here, you must be talkin’ to me.’”

I laughed. “I’ve heard the line, I’ve just never seen the movie.”

“You should watch it. You’d like it. Scorsese.”

The kook looked around suspiciously then leaned over as if he had some great secret to tell me.

“My name is Jesus Christ, Extraordinaire,” he confided. “Badda-bing, badda-boom.”

“I’m Nathan,” I said, shaking his hand. “Are you feeling all right? You were asking for a doctor, earlier …”

“I feel better now,” Jesus said.

“You sure?”

“Sure. I’d tell you if I didn’t.”

We sat in silence, looking around at the other people on the bus. I was sitting on a bus next to Jesus. It made me curious.

“So … who are you? What do you do?”

“This is what I do,” Jesus said. “This is my job.”

“The pay can’t be very good.”

“The pay is terrible,” Jesus lamented. “I only get what people give me. And they don’t usually give a whole lot. Hey, can I have a dollar?”

He went in a circle from person to person, asking for a dollar from each of them. They glared at him skeptically or ignored him outright. When Jesus came to man with a briefcase and necktie, he stopped and grinned.

“I know you have a dollar,” he said, winking. “I’ll bet you have several dollars.”

The man with a briefcase rolled his eyes and looked out the window.

“It’s OK, you don’t have to give me anything,” Jesus told him. “You don’t even have to say anything, or even look me in the eye. You don’t have to acknowledge I exist.”

Jesus became philosophical.

“You know, Nathan — it was Nathan, right? When I got on the bus, I looked around at all the people, and I knew that some of them I would talk to me, and some of them wouldn’t. I knew I could talk to you, and that you would talk to me. We’re following the same impulse, you know?”

It seemed wise to nod.

“But you,” — and here Jesus turned scornfully back to Mr. Briefcase — “I knew you wouldn’t talk to me. And it’s not just because you have a tie and a briefcase. You think I’m crazy, but also — you’re jealous. It makes you angry that I can sit here in my crazy clothes and say whatever I want, while you have to sit there in silence, because that’s who you are. It makes you really angry that I’m telling the whole bus about it, too. I’ll tell you what: You can keep your dollar. I don’t want it anyway.”

(Mr. Briefcase pulled the cord and got off at the next stop.)

I started to think that maybe Jesus Christ Extraodinaire wasn’t just a kook. He was kooky, sure, but part of him seemed deliberate and aware. I wondered if he was a graduate student in literature, fishing around for a story.

We talked about the ups and downs of begging for money. I told him about a bum I ran into a few weeks before, who had showed me a handful of silver coins and asked for only a nickel.

“He just wanted a soda,” I explained to Jesus. “He was 95 percent of the way there, he just needed that little bit to get him over the top. Now, we both knew that what he really wanted was $10 for a bottle of Jack, but he knew he couldn’t just ask for that. He was a bum with a plan — and maybe that’s the only kind of charity we’ll tolerate.”

Jesus pondered. He asked why a person couldn’t simply buy 95 cents worth of soda. It was because no one would buy an already-opened bottle, I suggested. It wouldn’t taste quite as good. People might be uneasy about it.

“So what?” Jesus asked. “Isn’t charity more important than a little uneasiness?”

I didn’t have a good answer to that. Granted, I have no problem with eating hot dogs that fall on the ground, so I’m biased. But he had a point.

“Well, think about that,” Jesus said, pulling the cord for the next stop.

We shook hands again, and then he disappeared into the grimy intersection of Mission Boulevard and Garnet.

When I got back to my apartment, I realized I was wearing a San Francisco Giants sweatshirt, which explained a lot. And when I watched “Taxi Driver” later that night, it explained a lot more. I’m still not sure if Jesus Christ Extraordinaire was genuinely insane or merely eccentric. (To be on the safe side, presidential candidates should probably stay away from Pacific Beach.) But whatever he was, I think he had something important to say.

True story.