Gloves for baby cats:
Kittens' Mittens

A happy flying elf:
Merry Fairy

Underwear for your cousin's mother:
Aunties' Panties

A stupid person who popped an enormous sticky bubble all over himself:
Gummy Dummy

Stupid William:
Silly Billy

Cold William:
Chilly Willie 
or 
Chilly Billy

A soft shaky stomach:
Jelly Belly

A frightening 
round juicy grape:
Scary Berry

A happy round juicy grape:
Merry Berry

A silly monster:
Funny Mummy

A rude Scottish girl:
A Sassy Lassie

A scary bright flash you see during a storm:
Frightening Lightning