Happy 50th anniversary, "A Charlie Brown Christmas!"

Good grief, "A Charlie Brown Christmas" turns 50 this year.

The animated special was first broadcast on December 9, 1965, and since then has gained a passionate following as a holiday classic. Here are some lesser known facts about "A Charlie Brown Christmas."

The special was originally commissioned and sponsored by the Coca-Cola company.

Coca-Cola had been looking for a special for advertising during the holidays. Charles Schulz, creator of the PEANUTS comic strip, and TV Producer Lee Mendelson began preparation for a PEANUTS Christmas special. According to Mendelson's book "A Charlie Brown Christmas: The Making of a Tradition," after pitching to Coca-Cola their ideas for a Christmas special, the two didn't receive any feedback for several days until the company confirmed they wanted to buy the special for an early December broadcast, giving Schulz and Mendelson just six months to produce.

It's believed Schulz based part of the special on his childhood in St. Paul, Minnesota.

Schulz grew up in the Minnesota metropolis, and many of the snowy images and scenes of ice skating are believed to reflect that, according to Mendelson's book.

Snoopy's dialogue is actually recorded gibberish sped up.

Snoopy has no spoken dialogue throughout the special except for muttering. It was suggested that spoken gibberish be recorded, and that would be later sped up for times when Snoopy makes any sort of verbal noise.

Kathy Steinberg, the voice of Sally Brown in the special, was just 6 years old during time of recording.

Since she was still too young to read, producers had to give Steinberg one line at a time to recite.

Popular rock group Jefferson Airplane was next door while the voices for the Christmas special were being recorded.

Members of the band then asked the children from the Charlie Brown special for their autographs afterwards.

The Vince Guaraldi Trio, composers of the famous Linus and Lucy theme, was picked for the special after Mendelson heard the trio on the radio.

Lee Mendelson heard a single on the radio from the trio titled "Cast Your Fate to the Wind." Mendelson then contacted Guaraldi and asked him to produce music for the special, resulting in the iconic theme.

"A Charlie Brown Christmas" airs Tuesday, Dec. 2 at 8:30 p.m. ET | 7:30 p.m. CT on ABC.