“The censors said, ‘No, you’re not allowed to show a bathroom.'”

Forget toilet humor sitcoms couldn’t evenshowtoilets back in the day.

“Twin beds and no toilet.”

The Brady Bunch, South Park

Maureen McCormick as Marcia Brady and Susan Olsen as Cindy Brady in ‘The Brady Bunch’; Mr. Hankey in ‘South Park’.Courtesy Everett Collection; Comedy Central / Courtesy Everett Collection

“How can a toilet tank be controversial?”

says Dow in the clip.

“That one still I don’t understand,” Knight says.

As sitcoms and TV in general began to push more boundaries, the depiction of restrooms changed too.

OnAll in the Family,“you heard a toilet flush.

And we sleep in the same beds,” star Sally Struthers says, feigning a dramatic gasp.

“That didn’t happen before.

We got real,” she adds.

South Parktook it to another level when they showed a piece of poo as a Christmas character.

SaysThe Brady Bunch’sEve Plumb, “We don’t need to see them going to the toilet anymore.”

History of the Sitcompremieres Sunday at 9 p.m. and 10 p.m. ET/PT on CNN.