Scrubmuffin

A person with little to no intelligence who's only goal in life is to spread their stupidity. All scrubmuffins are shit at life, and will therefore just shit all over everyone else's lives. Scrubmuffins will spend more time speaking sarcastically than sincerely, and many scrubmuffins will just sporadically switch between their plans for modes of transportation to places, disappointing and frustrating those around them.

That Luke kid is such a scrubmuffin. He told me he was going to catch the bus home, then he didn't.