What would be a good name for a mare that portrays her silliness and fun

For a fun pony, I'm thinking maybe Jolly, Joy, Giggles 或者 Smiley.

或者 if 你 want to focus on her silly (or even clumsy) side, then perhaps Klutzy 或者 Dizzy.

If 你 want to try something a little abstract, what about Roffle? As in, how 你 might pronounce ROFL when just 阅读 the four letters as a word rather than an acronym!

Anyway, I hope these ideas help 你 in some way! ^^