A kid normally of the male gender who happens to have a rat tail.
As you can tell by his rat tail his parents either don't care or are hoping he will grow up to be some sort of Jedi Knight such as Obi Wan Kenobi.
Rat Tail Kids take offense to other people making fun of them, and as a result have come up with witty comebacks to retaliate.
Person 1-"Hey Watch Out For Rat Tail Kid."
Rat Tail Kid-"You Guys Are Losers!"
Person 2-"That Was Rude Obi Wan."
Rat Tail Kid-"Go Poop Yourselves!!"