Kääntäkää tämä vitsi, jota en ymmärtänyt

Three men die on Christmas Eve and go to heaven, where they're met by St. Peter. "In order to get in," he tells them, "you must each produce something representative of the holidays."
The first man digs into his pockets and pulls out a match and lights it. "This represents a candle of hope." Impressed, Peter lets him in.
The second man pulls out a tangle of keys and shakes them. "These are bells." He's allowed in too.
"So," Peter says to the third man, "what do you have?"
The third man proudly shows him a pair of red panties.
"What do these have to do with Christmas?" asks Peter.
"They're Carol's."

Eli miten Carol liittyy jouluun?