The Dark Theory About Eric's Grandma In That '70s Show
That '70s Show loved to pull actors who were popular during the real-life bellbottoms era and cast them as side or guest characters. Chances are that this was done as a way to engage the older demographic that watched the show and give them a little treat. For instance, Tommy Chong took on a permanent side role on the show as the lovable burnout Leo. Marion Ross, who played Marion Cunningham on Happy Days, took on the role of Red Forman's (Kurtwood Smith) overly critical mother Beatrice. Then we come to Kitty Forman's (Debra Jo Rupp) mother Bea Sigurdson, who's played by a name that transcends generational gaps in a way few others have ever done: Betty White.
We only see Kitty's parents, Burt (Tom Poston) and Bea Sigurdson, a few times throughout the show. They're introduced on the fourth episode of season 5, entitled "Heartbreaker," and Bea is seen for the last time on "Babe I'm Gonna Leave You," the 14th episode of season 5. Burt, on the other hand, is absent from the show at that point. Why, you ask? Well, he was an old dude, and he wasn't about to live forever. In fact, it's Burt's death that has fueled a fan theory about his wife Bea — a theory too dark to have been on the show.
Bye-bye, Grandpa Sigurdson
The official reason for Burt's death, according to That '70s Show, was the heart attack he suffered outside the Forman residence while hiding from his wife, a thing he did quite often to avoid her deafening outbursts. Fans on the That '70s Show subreddit thread "Well this was a dark take..." don't seem to believe that's the whole story.
Earlier on in the episode where Burt bites the big one, "Your Time Is Gonna Come," it's revealed that he and Bea showed up to the Formans' house because they had nowhere else to go. Why? Because, as Reddit user u/perublanket39 points out, Burt lost all of their money when he purchased an ostrich farm. Now, as you might assume, Bea wasn't exactly pleased with his decision or the outcome of it, and some fans think she may have ... killed her husband over it.
"Because they lost all their money, Bea probably poisoned Burt to cause a heart attack so that she can have the insurance money/as revenge for losing all the money," u/perublanket39 theorizes. They also note that Kitty's mom didn't show much emotion over her husband's demise — which is honestly quite normal for the character, as she's portrayed as emotionally cold. It was kind of the focal point of the episode, actually.
But maybe Bea's yelling outbursts went beyond verbal patronization when the cameras were off. Maybe Kitty's mother had a more violent side that led her to murder her husband. It's a dark thought, and we'll probably never know for certain if it's true.