Big Head Mode

A common type of Silliness Switch is making all characters in a game have really big heads. For shooter games, this can make headshots easier to nail.

A distant cousin of Super-Deformed chibi versions of manga characters.

Shooters

 * Golden Eye 1997 has DK Mode, which also includes longer arms.
 * The Time Splitters series (which was made by a large number of the people who worked on GoldenEye after they left Rare) also had a big head mode cheat that could be unlocked (as well as a No head, tiny head and spinning head mode amongst others).
 * In Armor Games' Indestruc2Tank, one of the unlockable secrets is making the heads of people in comm units bigger.
 * Unreal Tournament 2003 had this as a mod.
 * Bionicle Heroes for the DS has this, making enemies easier targets.
 * Jak and Daxter games have unlockable (cheap) Big Head toggle. Some also have Tiny Head toggle.
 * As an unlockable Mutator in Gears of War 3, Big Head mode also pitches up everyone's chatter to match their silly proportions. Sadly, it does not apply in cutscenes.

Sports Games

 * NBA Jam is the likely Trope Codifier, appearing as a Classic Cheat Code in most of Midway Games's arcade versions, and also in the EA Sports Revival.
 * NFL Blitz has a big heads code in almost every game in the series.
 * A cheat in some Tony Hawks Pro Skater games.

Other Games

 * The original Spyro the Dragon trilogy had a code for that.
 * Tekken 2 has this, being released in 1996 when Big Head Mode was popular. It hasn't returned in any sequels.
 * In Toontown Online, one of the rewards for completing a "Just for Fun" Task is your Toon to receive a giant head for a varying period of time, depending on which Playground tasks you're working on.
 * One of the game mods of Wasted Youth.
 * In Mortal Kombat 4, this is one of the Kombat Kodes. For some reason, it also affects the skeleton hands that Shinnok summons in his fatalities. In one of them, they get too big to fit through the portal.
 * Batman Arkham City has this.
 * Banjo-Kazooie had several unlockable cheats to enlarge the head, arms, legs or all at once of Banjo and Kazooie.

Non-Video Games

 * Emporio Ivankov can do that in One Piece.
 * Soun Tendo from Ranma One Half tends to do this when upset (usually when finding yet another long lost fiancée or the like that Ranma has been promised to marry), sometimes with demonic assets like a snake's tongue or tentacles.