An idea for a fun joke spell that isn't just a reskin of vermillio is Anaticula, perhaps for an event. Anaticula has a simple effect on the target, where the target's spells now only produce ducks instead of the desired effect. An example would be:
Wizard 1: *casts Anaticula*
Wizard 2: *casts Stupefy*
Wizard 2's Wand: Produces live duck rather than intended stunning spell
This spell would be a jinx type spell with a Crowd Control category. The easiest way to implement it would be something similar to the Stupeficus spell, whereas instead of stopping spells cast, it instead produces a duck. There would be exceptions, such as high-levelled spells, or utility spells. An effective cooldown would be 35 seconds, with a duration of 5 seconds, to prevent constant inability to use spells. So, in summary:
Anaticula
Jinx: Causes opponent's wand produce ducks instead of intended spells
Category: Crowd Control
Cooldown: 35 seconds
Range: 28 meters
Duration: 5 seconds
Cost: 35 magic
Wizard 1: *casts Anaticula*
Wizard 2: *casts Stupefy*
Wizard 2's Wand: Produces live duck rather than intended stunning spell
This spell would be a jinx type spell with a Crowd Control category. The easiest way to implement it would be something similar to the Stupeficus spell, whereas instead of stopping spells cast, it instead produces a duck. There would be exceptions, such as high-levelled spells, or utility spells. An effective cooldown would be 35 seconds, with a duration of 5 seconds, to prevent constant inability to use spells. So, in summary:
Anaticula
Jinx: Causes opponent's wand produce ducks instead of intended spells
Category: Crowd Control
Cooldown: 35 seconds
Range: 28 meters
Duration: 5 seconds
Cost: 35 magic