Jon Hamm completed a 30-day rehab program for alcohol abuse, just days before the premiere of the last season of "Mad Men."

We're told Hamm checked himself into Silver Hill Hospital in New Canaan, Connecticut at the end of February. It's a high-end facility.

The final season is already in the can.

Hamm's people tell TMZ, "With the support of his longtime partner Jennifer Westfeldt, Jon Hamm recently completed treatment for his struggle with alcohol addiction. They have asked for privacy and sensitivity going forward."

The woman who passed over Jon Hamm on a dating show back in 1996 would do it all again ... telling TMZ Live she wouldn't trade her husband for "one thousand Jon Hamms!"

As TMZ first reported, the man who would be Don Draper appeared on a show called "The Big Date" long before appearing on "Mad Men" ... and got passed over by TWO different women on the show.

TMZ Live managed to track down Mary, one of the women from the show, who says she is aware Hamm went on to become famous ... but says she's never seen an episode of "Mad Men."

What she was not aware of ... was Hamm's reputation in the man region. Of course ... we told her.

The worst decision you've ever made doesn't compare to the two women who DID NOT pick Jon Hamm on a dating show waaaaay before he hit it big.

Back in 1996, 25-year-old Hamm looked like Don Draper -- if he was in the witness protection program -- when he went on a show called "The Big Date" ... hosted by Mark L. Walberg, who now hosts "Antiques Roadshow."

The folks at Lighthearted Entertainment unearthed this clip where a surfer dude-looking Hamm
gets passed over for TWO other guys ... one of 'em even had frosted tips!

Firefighters raced to Jon Hamm's Los Feliz home this morning after a smoke alarm went off ... but fear not, TMZ has learned the "Mad Men" star was never in any real danger.

Two fire trucks rolled up at 9:19 AM and firefighters went inside ... by 9:22 AM, they were on their way out after determining the whole thing was a false alarm.

We spent 10 minutes trying to think of a Jon Hamm "fire hose" joke ... but couldn't -- so, feel free to insert your own here.

Have a great Monday.

Unlike on "Mad Men," Don Draper's first wife Betty (aka January Jones) and his 2nd wife Megan (aka Jessica Paré) made nice at an event in NYC this week.

Question is ...

There's a mad scramble under way to get into Jon Hamm's pants -- with two of the biggest underwear companies on the planet hoping to win the affection of Jon's junk ... TMZ has learned.

The undie brands gunning for Jon's crotch are Fruit of the Loom and Jockey -- which both reached out to Hamm after reports surfaced that "Mad Men" producers asked Hamm to stop going commando on set because his dong was visible through his clothes.

TMZ has learned ... both companies have reached out to Hamm in the hopes of remedying the alleged problem ... with FREE UNDERWEAR FOR LIFE!!!

A rep for Jockey told us ... "Jockey would like to offer our support for Jon Hamm in the form of a lifetime supply of Jockey underwear. "

The Fruit of the Loom people also have a message for Jon -- "We want people to be themselves. And if going Commando makes you happy, we say go for it. But in case you change your mind, we got you covered."

For his part, Jon hasn't confirmed the commando rumors ... despite the fact that there are a TON of pics on the Internet of his moose knuckle in full swing.

"Mad Men" lovelies January Jones and a covered up Christina Hendricks both put their hair back at the same event in NYC this week.

Question is ...

As we first reported Jones was driving home last night when her car struck 3 parked vehicles. She left her license with a witness, walked a short distance to her home, called 911 and eventually returned to the scene. Jones told cops paparazzi were following her and that's why she crashed. Cops did not administer a field sobriety test -- we were told because there was no evidence of alcohol.

But now we're getting a more involved story. A woman who owns one of the cars that was hit tells TMZ ... she heard the crash, looked over her balcony and saw Jones. She says around 10 minutes after the crash, Food Network star Bobby Flay showed up in a separate car, began talking with her and telling her to leave the scene, which she did.

We spoke with Flay, who tells us he was watching the basketball game last night at The London West Hollywood Hotel with a group of people that included Jones. Flay says he saw her drink a beer but wasn't really watching her alcohol intake. Flay says he had only met Jones once before, and last night she asked for his number because she wanted to redo her kitchen and give his number to her designer. Flay obliged, and says he doesn't know why Jones chose to call him after the crash, but nonetheless he drove over to help her. He says he did not argue but just wanted to make sure she was ok.

The witness at the scene tells TMZ she was face-to-face with Jones and smelled alcohol on her breath. The witness says Jones left her driver's license with another resident and left. She returned 45 minutes later in a different set of clothes, chewing gum.

The witness says she asked cops if they were going to administer a field sobriety test, but a cop told her there was no point since she could have had a drink at home and there was no way of proving she was under the influence when she was behind the wheel. Cops confirm there is no way to pin drinking and driving on someone who leaves the scene and comes back.

As for being chased by the paparazzi ... none of the witnesses we spoke with saw any photogs at the scene, and no pictures have surfaced that show the scene immediately after the crash. The pics you see in this post were taken many hours later.

Jones' reps have not returned our calls.