The show took place earlier this month but it was broadcast on Wednesday night (December 26) - and Cher was watching.
Lambert hit the stage to sing his rendition of Cher's 1998 hit "Believe", while Cyndi surprised the diva with a cover of "If I Could Turn Back Time", leaving the pop veteran a mess of emotions.
"Tried 2 write Feelings About Adam Lambert Singing Believe In Words,but Cant seem 2.When Your senses are Overwhelmed All Can you feel with your (heart)," Cher tweeted after watching the telecast, while at the gig she scolded Lauper for lying about her whereabouts.
"You told me you were going to Los Angeles!" Cher shouted from the balcony as Lauper took the stage, responding, "I lied."
Tried 2 write Feelings About Adam Lambert Singing— Cher (@cher) December 27, 2018
Believe In Words,but Cant seem 2.When Your senses are Overwhelmed All Can you feel with your ❤️.
I Was Shocked AND Over The MOON When Cindi (Lauper) came out Rocking the house.
Shocked Because SHE TOLD ME SHE WAS IN LA,
In addition to Cher, Reba McEntire, "Hamilton" creator Lin-Manuel Miranda, pianist Philip Glass, jazz saxophonist and composer Wayne Shorter, director Thomas Kail, choreographer Andy Blankenbuehler, and music director Alex Lacamoire were all honoured at the 2018 Kennedy Center Honors.