Aaron Key wasn't sure he wanted a tattoo on his neck. Especially one of a giant squid smoking a joint.

But the guys running Squid's Smoke Shop in Portland, Ore., convinced him: It would be a perfect way to promote their store.

They would even pay him and a friend $150 apiece if they agreed to turn their bodies into walking billboards.

Key, who is mentally disabled, was swayed.

He and his friend, Marquis Glover, liked Squid's. It was their hangout. The 19-year-olds spent many afternoons there playing Xbox and chatting with the owner, "Squid," and the store clerks.

So they took the money and got the ink etched on their necks, tentacles creeping down to their collarbones.

It would be months before the young men learned the whole thing was a setup. The guys running Squid's were actually undercover ATF agents conducting a sting to get guns away from criminals and drugs off the street.

The tattoos had been sponsored by the U.S. government; advertisements for a fake storefront.

The teens found out as they were arrested and booked into jail....

Tony Bruner was looking for a job when he noticed a new store opening a few blocks from where he lived with his grandmother in a lower-income neighborhood in Wichita just east of Interstate 135.

With an IQ in the mid-50s — considered extremely intellectually deficient — Bruner hadn't been able to hold down a job. His 2009 felony burglary conviction didn't help. Still he was under pressure from his probation agent and grandmother to find work.

Bruner hadn't heard of Bandit Trading, but the thrift shop full of hip-hop clothes and shoes looked like a good prospect when he walked in.

The 20-year-old Bruner was just what undercover agents running the store were looking for.

Agents could see Bruner was intellectually disabled. On a video of one of their first meetings in November 2010, agents referred to him as "slow-headed," according to Griffith, Bruner's attorney.

"It was essential to have someone like Tony or your low-IQ guy in Milwaukee for this operation," Griffith said. "These 30-something bearded and tattooed white guys aren't going to knock on doors in the hood and say 'Do you have guns?' They had to get someone to do it for them."

Agent Jason Fuller hired Bruner to hand out cards in the neighborhood; do odd jobs, such as clean up the parking lot; and watch out for police. The agents paid him in cigarettes, clothing from the store and cash — $20 to $50 in commission to find them electronics and other goods. And they took him to McDonald's when he was hungry.

Eventually they asked him to find guns.

Bruner said he didn't have any but he would try to find some. He ended up brokering dozens of gun sales.

And then, they arrested him on more than 100 counts of being a felon in possession of a weapon....

ATF agents running an undercover storefront in Milwaukee used a brain-damaged man with a low IQ to set up gun and drug deals, paying him in cigarettes, merchandise and money, according to federal documents obtained by the Journal Sentinel.

For more than six months, federal agents relied on Chauncey Wright to promote "Fearless Distributing" by handing out fliers as he rode his bike around town recommending the store to friends, family and strangers, according to federal prosecutors and family members.

Wright, unaware that the store was an undercover operation being run by agents with the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives, also stocked shelves with shoes, clothing, drug paraphernalia and auto parts, according to his family.

Once authorities shut down the operation, they charged the 28-year-old man with federal gun and drug counts....