The old saying “Sally sold seashells by the seashore” has nothing on a tongue twister created by researchers at MIT. The verbal puzzle, “pad kid poured curd pulled cod,” tripped up test subjects who tried to spit out so much, that psychologists believe it could be the toughest one there is to date.

“If anyone can say this [phrase] ten times quickly, they get a prize,” said Stefanie Shattuck-Hufnagel, a psychologist from MIT who specializes in speech errors as a way of understanding normal brain functions, and one of the creators of the mouth-boggling phrase.

On Thursday Shattuck-Hufnagel is presenting her research about the comparison of two types of tongue twisters, including the difficult phrase, at the Acoustical Society of America in San Francisco. The presentation will be based on research conducted with a team from MIT, where scientists recorded the misspoken sounds for terms like “top cop,” and “toy boat,” to see what errors people produced.