(USA TODAY) - It makes Jessica Simpson's Chicken of the Sea-or-tuna spectacle seem almost charming.

Bravo's Real Housewives have said a lot of really outrageous/terrifying/(insert adjective) things over the years, but the firm belief by Atlanta's 31-year-old Porsha Stewart that the Underground Railroad was a real railroad with a real train left even her co-stars grasping for words.

"Ding. Dong," NeNe Leakes said on Sunday's show.

"It's almost hurtful to watch her be so dumb," Kenya Moore said.

The epic gaffe occurred while the women were touring the First African Baptist Church in Savannah, Ga. The tour guide pointed to ventilation holes in the wood floor, below which lay a 4-foot-high crawl space, a small part of what every third grader learns: the Underground Railroad.

"There had to be an opening for the railroad at some point," reasons Stewart, whose ex is former NFLer Kordell Stewart. "Somebody's driving the train. It's not electric like we have now."

The women pounce. "It wasn't a train," Phaedra Parks explained. "It was a euphemism, baby. A figure of speech."

Then they proceed to give her the history lesson we can only hope she simply slept through.

Check out some ofour mostread stories from 2013:

#shortyellows:Florida quietly shortened yellow lights

Terrorism Warning:Memo says terrorists practicing dry-runs on Florida flights

Kittens shot:Officer shoots kittens in front of children

Courtroom apology:Woman apologizes for flipping off judge

Weird ice:Strange, giant circles appear on frozen pond

Controversial Club:College student organizes "White Student Union"

CFO Trouble:School administrative chief in trouble over her porn sex blog

Warning Shot Wife:Mother gets 20 years for firing warning shots at abusive husband

Science Arrest:Teen girl arrested over science project explosion

Wait, WHAT??Dog shoots man in the leg with a handgun

Popular photo galleries:

Faces of Meth:Devastating before and after photos of meth abusers

Trayvon Martin Shooting:Trayvon Martin crime scene photos and George Zimmerman injury photos

Hooters Winners:Winners of the 2013 Hooters swimsuit pageant

Rejected:Funny Florida license plates rejected by the DMV***warning graphic***

Deadly sinkhole:Home collapses, man dies in giant sinkhole

Popular Databases:

Florida Sex Offenders:Look up sex offenders in any Florida neighborhood here

Restaurant Inspections:Look up inspection reports for any Florida restaurant here