I didn't say anything. I'd been giddy and angry. Now I was scared witless.

"I'm sorry," I managed, hating myself again for saying it.

Booger got in the front seat and Zit put the car in gear, cruising up 24th Street and over Potrero Hill. They had my address from my ID.

Mom answered the door after they rang the bell, leaving the chain on. She peeked around it, saw me and said, "Marcus? Who are these men?"

"Police," Booger said. He showed her his badge, letting her get a good look at it -- not whipping it away the way he had with me. "Can we come in?"

Mom closed the door and took the chain off and let them in. They brought me in and Mom gave the three of us one of her looks.

"What's this about?"

Booger pointed at me. "We wanted to ask your son some routine questions about his movements, but he declined to answer them. We felt it might be best to bring him here."

"Is he under arrest?" Mom's accent was coming on strong. Good old Mom.

"Are you a United States citizen, ma'am?" Zit said.

She gave him a look that could have stripped paint. "I shore am, hyuck," she said, in a broad southern accent. "Am I under arrest?"

The two cops exchanged a look.

Zit took the fore. "We seem to have gotten off to a bad start. We identified your son as someone with a nonstandard public transit usage pattern, as part of a new pro-active enforcement program. When we spot people whose travels are unusual, or that match a suspicious profile, we investigate further."

"Wait," Mom said. "How do you know how my son uses the Muni?"

"The Fast Pass," he said. "It tracks voyages."

"I see," Mom said, folding her arms. Folding her arms was a bad sign. It was bad enough she hadn't offered them a cup of tea -- in Mom-land, that was practically like making them shout through the mail-slot -- but once she folded her arms, it was not going to end well for them. At that moment, I wanted to go and buy her a big bunch of flowers.

"Marcus here declined to tell us why his movements had been what they were."

"Are you saying you think my son is a terrorist because of how he rides the bus?"

"Terrorists aren't the only bad guys we catch this way," Zit said. "Drug dealers. Gang kids. Even shoplifters smart enough to hit a different neighborhood with every run."

"You think my son is a drug dealer?"

"We're not saying that --" Zit began. Mom clapped her hands at him to shut him up.

"Marcus, please pass me your backpack."

I did.

Mom unzipped it and looked through it, turning her back to us first.

"Officers, I can now affirm that there are no narcotics, explosives, or shoplifted gewgaws in my son's bag. I think we're done here. I would like your badge numbers before you go, please."