The reality star also accidentally reveals her secret Saturday afternoon plans and share what she's convinced Oprah Winfrey to do.
UPDATED 3:19 p.m. on 1/10/19:
Jax took to Twitter to set the record straight.
"Not that I care, it was over 10 years ago and I am happily engaged, but she's a liar," he tweeted Thursday afternoon, along with a screenshot of a text message from his friend who was allegedly there that night. "My two friends who have nothing to gain were with me the whole night. That's all I will say on this. So you are lying, darlin'." See everything else he said here.
Lindsay Lohan lamented, "I'm just so honest, I hate it," during her appearance with Andy Cohen on "Watch What Happens Live" Wednesday night, and it kind of seems like she just might be.
The star of "Lindsay Lohan's Beach Club" on MTV played a game of "Plead the Fifth," but she never hesitated to say what was on her mind, even if it meant calling a Bravo reality star a liar or accidentally blurting out her plans for Saturday afternoon.
That was doubly problematic as she not only exposed to all of America where she'll be and when, she also totally blew a planned surprise by simply speaking her truth almost before thinking anything through.
Even after revealing her biggest regret, she said, "Well, it's truthful. Is that bad?"
She was at her most candid during Cohen's iconic "Plead the Fifth" game, where he asked her a couple of questions, and brought Lisa Vanderpump on to ask another.
Lisa's question was a callback to the "Vanderpump Rules" star's "WWHL" appearance, in which he said he'd once hooked up with LiLo. "Describe him as a lover in three words," Lisa asked, expecting some juice. She got some, but not what she was anticipating.
"Lisa, I love you but I've never even met him," Lindsay said. When pressed by Andy, she insisted. "I've never met him. Really!"
Finally, he asked her if she was calling Jax a liar. Her simple response: "Yes."
Lindsay also said that her biggest life regret was drinking and driving and explained why she threw some shade at Kim Kardashian a few years back when she commented on her braids. The comment led to a shade trade with Kim asking her about her ever-changing accent.
Laughing, Lindsay explained, "I love Kim, I just was confused about the braids because she just had a baby."
When asked about her relationship with Oprah Winfrey, Lindsay admitted she'd spoken to her just last month. "I asked if she wanted to come to Mykonos next summer. She said yes, let's talk in a month." Andy quickly pointed out that it's been a month.
So does that mean there's an outside chance of an Oprah appearance on "Lindsay Lohan's Beach Club" should it get a second-season renewal? That chance alone should have MTV ready to re-up.
It would also give the actress a new chapter in the long-gestating tell-all. She gave Andy an update on her progress and ambition for the book that she's been working on for four years.
"I write through poetry, so I want to write inspirational thoughts that I've had, and I want to relate to younger people so they can have a book to guide themselves as well," she said. "So I'm doing two books kind of in one."
Elsewhere in the show, Lindsay totally blew her own surprise when Andy asked her about having not seen the "Mean Girls" musical on Broadway yet. "No, I have to go see it because the girls were so nice. They came to the premiere of the show, so I'm gonna do it with my sister I think, Saturday matinee."
Realizing what she'd just done, she quickly added, "I should not have just said that out loud." Well, her sister can be surprised that Lindsay just blurted out on national television where they'll be Saturday, and the cast of "Mean Girls" can be excited about a guaranteed sold-out showing.
Lindsay looked to be having a good time hanging with Andy, even though the frenetic pace of "WWHL" certainly seemed to keep her on her toes, but nowhere was she having more fun than when Andy decided that she should reenact a scene from "The Parent Trip" with him playing her twin.
It was the wig and his awful English accent she couldn't get past. "Your English accent, that was, like, everything," she praised him, as fellow guest Danielle Staub told him it was awful.
It was no worse, we think, than his attempt at doing "The LiLo" -- the viral challenge Lindsay inadvertently created by dancing in a very ... ahem ... unique way during taping of her show in Mykonos.
As Lindsay had no interest in doing it -- she's totally embarrassed by the whole thing -- Andy instead decided that he would "audition" for her and show her his best take on it. All we can say is it was certainly enthusiastic. Check out his take in the video below: