I'll explain what the title means:

Suppose you get the word "clove" to sketch. You don't know what a clove is, but you know that if you can get the players to guess "clover", you'll succeed at sketching it. (Which I did :D)

Also, I've seen someone sketch "library" to get the players to guess "libra".

This isn't a major problem, but seeing as it is technically not in the spirit of the game (it's impossible in Pictionary; xsketch input analysis makes it an exploit) we should probably discuss whether it's worth preventing it, perhaps by checking guesses against a list of invalid guesses for each word.