WASHINGTON . WHEN Willie Nelson invites you to get high with him on his bus, you go.

The man is the patron saint of pot, after all, and I’m the poster girl for bad pot trips.

It seemed like a match made in hash heaven.

When Nelson sang at the 9:30 club in D.C. one recent night, I ventured onto the Honeysuckle Rose, as his tour bus and home-away-from-home is called.

I was feeling pretty shy about meeting him. The 81-year-old Redheaded Stranger is an icon, one of America’s top songwriters and, as Rolling Stone said, “a hippie’s hippie and a redneck’s redneck.” The Smithsonian wants his guitar, “Trigger.”I needed a marijuana Miyagi, and who better than Nelson, who has a second-degree black belt in taekwondo and a first-degree black belt in helping Norml push for pot legalization?In a Rolling Stone cover piece last month on “America’s Most Beloved Outlaw,” Nelson told writer Patrick Doyle that he had read my column on having a bad reaction to a marijuana-infused candy bar while I was in Denver covering the pot revolution in Colorado.

“Maybe she’ll read the label now!” he said, laughing, adding that I was welcome to get high on his bus “anytime.”So that’s how I found myself, before Nelson’s show here, sitting opposite him in a booth on the bus as he drank black coffee out of a pottery cup, beneath a bulletin board filled with family photos.

His eyes were brass-colored, to use Loretta Lynn’s description. His long pigtails were graying. His green T-shirt bore the logo of his son’s band, Promise of the Real.

So, Sensei, if I ever decide to give legal pot a whirl again, what do I need to know?“The same thing that happened to you happened to me one or two times when I was not aware of how much strength was in whatever I was eating,” Nelson said, in his honeyed voice. “One time, I ate a bunch of cookies that, I knew they were laced but I didn’t worry about it. I just wanted to see what it would do, and I overdid it, naturally, and I was laying there, and it felt like the flesh was falling off my bones.

“Honestly, I don’t do edibles,” he continued. “I’d rather do it the old-fashioned way, because I don’t enjoy the high that the body gets. Although I realize there’s a lot of other people who have to have it that way, like the children that they’re bringing to Colorado right now for medical treatments. Those kids can’t smoke. So for those people, God bless ‘em, we’re for it.”Eager not to seem like a complete idiot, I burbled that, despite the assumption of many that I gobbled the whole candy bar, I had only taken a small bite off the end, and then when nothing seemed to be happening, another nibble. Nelson humored me as I also pointed out that the labels last winter did not feature the information that would have saved me from my night of dread.

Now, however, Colorado and Washington State have passed emergency rules to get better labeling and portion control on edibles, whose highs kick in more slowly and can be more intense than when the drug is smoked. Activists are also pushing to make sure there are stamps or shapes to distinguish pot snacks . which had, heretofore, been designed to mimic regular snacks . so that children don’t mistakenly ingest them.

Trying to prevent any more deaths, emergency-room trips or runaway paranoia, the Marijuana Policy Project has started an educational campaign called “Consume Responsibly.”Its whimsical first billboard in Denver shows a bandjaxed redhead in a hotel room . which is far too neat to be mine . with the warning: “Don’t let a candy bar ruin your vacation. With edibles, start low and go slow.”Bill Maher also offered Colorado, “the Jackie Robinson of marijuana legislation,” some tips, including having budtenders talk to customers “like a pharmacist would,” curtail pot products that look like children’s candy, and don’t sell novices kief, superconcentrated crystals so potent that they’re “harvested directly from Willie Nelson’s beard.”I asked Nelson about Jerry Brown’s contention that a nation of potheads would threaten American superiority.

“I never listened to him that much,” he said, sweetly.

He showed me his pot vaporizer, noting: “Everybody’s got to kill their own snakes, as they say. I found out that pot is the best thing for me because I needed something to slow me down a little bit.” He was such a mean drunk, he said, that if he’d kept drinking heavily, “there’s no telling how many people I would have killed by now.”I asked him about the time he was staying in the Carter White House . on bond from a pot bust . and took a joint up to the roof.

“It happened a long time ago,” he said, adding slyly, “I’m sure it happened.”Did he also indulge in the Lincoln Bedroom?“In what?” he replied, mischievously. “I wouldn’t do anything Lincoln wouldn’t have done.”Given all the horrors in the world now, I said, maybe President Obama needs to chill out by reuniting the Choom Gang.

“I would think,” Nelson said, laughing, “he would sneak off somewhere.”