Irene is one of a set of identical triplets. One of her sisters always tells the truth, and the other one always lies. Irene sometimes is truthful and sometimes isn't.
The triplets are dressed in identical outfits except for the ribbons in their hair. One girl has a blue ribbon, one a green ribbon, and one a red ribbon.
"Irene?" you call out, questioningly.
"That's me," says the girl wearing a blue ribbon.
"Yep, she's Irene," agrees the girl wearing a green ribbon.
"I'm definitely not Irene," says the girl wearing a red ribbon.
Which triplet is Irene?