Contagious Laughter: When Charles' hair has been turned green by dye (after accidentally tripping a trap set by Laura for the "Creeper"), he attends Sunday services and immediately elicits raucous laughter from all in attendance. When the Reverend Alden enters, he's initially perplexed by the guffawing (which gradually dies down upon his arrival), but then sees the cause, and visibly struggles to ignore it. But once Alden announces that the 23rd Psalm will be the subject for today's sermon (taking pains to point out that he selected it days before), upon reciting "He maketh me to lie down in green pastures!", the good Reverend LOSES IT, exploding into uproarious laughter, and the rest of the congregation joins him.
Et Tu, Brute?: When everyone starts laughing at Charles, Caroline tries to keep herself from laughing, but once Charles leaves the church, she explodes into laughter.
Justified Criminal: The "Creeper" turns out to be Timothy Farrell, an aspiring doctor whose father is recovering from a heart attack and now he needs to care and provide for him while studying for an examination to become a doctor. He did try to find an honest job, but couldn't find one anywhere and his father, a prideful man, refuses to accept any charities. So he retorted to stealing food to keep his father nourished, never taking any money or anything too valuable. When Laura and Andy find it out and explain it to Charles, he discusses with the town elders and they decide Timothy doesn't deserve jail and announce they will look after his father while he's off to become a doctor, and when he goes back, he'll owe each of them a free visit in exchange (also for the robberies, which his father never learns about).
Kid Detective: Laura and Andy are inspired by Fremont books to become amateur detectives and investigate the stealings in Walnut Grove. Their attempts to emulate their idol are, clumsy to put it mildly and cause more trouble than solve it. It's by sheer luck that they figure out the Creeper's identity, though they decide to be compassionate about his situation by discussing things with Charles rather than turn him in and take the reward offered by Mrs. Oleson.
Not So Above It All: Not only Reverend Alden, but several characters who'd otherwise feel sorry for a friend in an embarrassing situation (Nels, Ms. Beadle, Jonathan and Alice Garvey) explode in laughter upon seeing Charles's hair dyed green. Even Caroline can't hold her laugh much longer.
Screw This, I'm Outta Here: Poor Charles' very reasonable reaction to the entire church congregation bursting into uncontrolled laughter over his newly verdant hair follicles.
