

When Jack shows them the exact symbol of the Christmas tree door they were meant to go through, Lock quickly looks over at his cohorts and fidgets with his hands nervously, implying that it was he who suggested the Easter door. However, they mistakenly kidnap the Easter Bunny instead.

Lock makes another appearance with Shock and Barrel again with their first try of kidnapping "Sandy Claws". In their song, Kidnap the Sandy Claws, he suggests boiling "Sandy Claws" alive and buttering him up, then later shoots Barrel out from their cannon after demonstrating that " Sandy Claws will be no more!” The three then leave for their treehouse, and Lock says that he wants to kidnap "Sandy Claws" before they all agree to do it together. He then says ''wouldn't dream of it jack'' but crosses his fingers behind his back, like Shock and Barrel. After being told their task, he is the first one who tries to leave until Jack pulls him back by his tail, grabs him and bringing him up to his face, angrily warns him and the others to " leave that no-good Oogie Boogie out of this!" throwing him back down with his cohorts. Lock is first introduced when Jack Skellington summons him and his cohorts for their Christmas assignment of kidnapping "Sandy Claws". Lock shares the same twisted and morbid ideas as Shock and Barrel do.

When he disagrees with his own ideas or can't come up with any himself, he'll go along with his friends' plans if they have a better picture for mischief. He shows apt logical thinking (such as when saying " Sandy Claws" can fit down both chimneys and Oogie's sacrifice tunnel) and highly active initiative, which usually has him driving and kindling the trio toward their shared goals with a sense of fierce, impish amusement. Lock often quarrels with the other two Trick-or-Treaters and is quite easy to offend. Despite being 6 years old, his voice is a little deep. He, along with Shock and Barrel, wears a mask to accompany his devil getup - which is a standard red mask with narrow slits for the eyes and two pointed horns at the top, resembling closely to a red devil. His mouth is blue and he wears a standard red shirt, pants, and shoes, with a devil-like tail sticking out of his clothes, also being a natural part of his body. Lock is a six year old boy, he has a tall and narrow face with red hair and two wavy bangs.
