Fifth Harmony is still on cloud nine after hitting the stage with Taylor Swift on the Santa Clara, California, stop of her 1989 tour.

"It was amazing! It was honestly -- it was a dream come true," 5H's Camila Cabello gushed to ET on Sunday's Teen Choice Awards red carpet. “Sixty-five thousand people in the stadium -- and she learned the choreography, wore our tour outfit -- it was seriously a night we'll never forget."

WATCH: Fifth Harmony Talks Summer Tour

Swift Instagrammed about about being "twinzies" with the girl group over the weekend and "cuddling" on-stage with pals Cabello and Ally Brooke. The girls all donned matching blue costumes for their performance of Fifth Harmony's hit single, "Worth It," on Friday.

WATCH: Taylor Swift Gets Personal and Friends and Romance

"It was just like a beautiful dream," Brooke said on Sunday. "Just euphoria. So magical!"

5H's Lauren Jauregui dished on getting to work with the "Shake It Off" singer, calling her "really dope."

"She was really welcoming," Jauregui said. "She's really quirky -- a cool girl."

Do we even need to say it? Serious #SquadGoals.

Get to know the girls of Fifth Harmony in ET's Artist to Watch feature, below.