Steven deForest is an experienced air traveler, but he says nothing could have prepared him for the confrontation he recently had with a TSA screener in Las Vegas.

“I chose to opt out of the backscatter X-ray and submit to a physical search,” he says.

DeForest was ushered into a glass holding box until a screener could be found to conduct the search.

“A bulky young TSA agent came over to pat me down,” he remembers. “He told me to turn around. He was using his command voice, barking orders. I told him that I wasn’t comfortable turning away from my luggage, which had already been screened, and wanted to keep it in my sight.”

The agent issued more orders — “Stay there, I didn’t tell you to move!” and “Empty your pockets!” — and deForest says the federal screener seemed irritated that he didn’t obey him without hesitation.

And that’s when deForest says he was punished. The agent knelt in front of him to conduct a pat-down.

“As he raised his hands he was looking at me,” he says. “Then he gave a quick flick and smacked me in one of my testicles.”

The TSA says its full-body scanners are optional and that it trains its agents to treat “opt-outs” like deForest with respect. But during the last few weeks, a different picture has emerged from within the TSA’s own ranks.

Passengers are complaining that TSA agents are punishing them for failure to comply quickly to their orders, or simply for opting out, an allegation that TSA insiders admit is true.

The most troubling is the case of former TSA agent John Irwin, who admitted to stealing $520 from a passenger because the passenger wasn’t deferential enough to him.

The scenario was virtually identical to deForest’s. Last November, a passenger asked to opt out of the full body scanner, and when he complained at being led into a private screening area, Irwin removed $520 in cash that had been screened and hid it in a TSA supervisor’s drawer.

And who can forget the woman who missed her flight last month because of her bad “attitude”? It might be difficult to believe a TSA agent would prevent her from making her flight, except that the incident was captured on video and posted to YouTube.

The latest wave of complaints about TSA agents punishing passengers isn’t new. Back in 2010, when the TSA began using full-body scanners, I spoke with passengers who said the pat-downs were retaliatory. But this is one of those rare times when TSA agents essentially agree that their actions at the screening area are intended to punish rather than protect airline passengers.

Of course, some passengers understand that airport screening is a game, and they seem ready to turn the tables. When this woman was told she couldn’t bring her vodka through a checkpoint last week, she retaliated by drinking it. At 7:30 a.m.

Imbibing distilled spirits before being screened is totally legal, by the way — but I wouldn’t recommend it.

But most passengers probably feel a lot like deForest, the passenger whose genitals were rapped in Las Vegas: upset, but ultimately powerless to stop it from happening.

“I can’t over-emphasize the feeling of humiliation, rage, and frustration,” he told me. “I believe I have a better idea of what a woman feels when she is groped, or worse. I was deliberately assaulted by someone who knew that he could get away with it.”

He’s right. Unless an agent comes forward to confess that he or she intentionally roughed up a passenger, or stole money from him, or made her miss her flight, it’s hard to prove anything.

A delay in screening a passenger can seem like punishment, but who knows, the screening area might be short staffed? Valuables can go missing from a tray, but how can you be sure another passenger didn’t accidentally take it?

And a pat-down can look proper, but it can feel like rape.