In a segment in the special, all of the children go trick-or-treating (except for Linus van Pelt and Sally Brown, who sit in a pumpkin patch waiting for the Great Pumpkin). At each house they call at, most of the children receive large amounts of candy or other treats and excitedly tell their friends about it afterwards. However, in every case Charlie Brown says, "I got a rock", with increasing disappointment as the miscreant minerals pile up in his bag instead of candy.
Charlie Brown's bad luck trick-or-treating earned him a lot of sympathy amongst young viewers, to the extent that some mailed candy for Charlie Brown to the TV channels that aired the special.
In recent years, many fans have viewed the gag as disturbing, seeing it as even the adults hating Charlie Brown that they would willingly conspire to deny him candy. Many have also said that realistically, anyone getting a rock for Halloween would inevitably weaponize it in retaliation for not getting candy.
"I got a rock" also features in the Peanuts comic strip from November 1, 1975, following a Halloween storyline in which Peppermint Patty is convinced by Linus to wait for the Great Pumpkin, who, of course, does not show up. Peppermint Patty is very upset that she missed trick-or-treating. Charlie Brown expresses his disappointment that all he ended up with in his candy bag was a rock. Peppermint Patty says, "I sat in a pumpkin patch for a week, and I didn't get ANYTHING!" to which Charlie Brown replies, "Do you want my rock?"