Sniggle

A sniggle is someone who acts like they think they're doing nothing wrong, but at any given moment is terrorizing everyone around them with their faceless persona and nonchalant actions. Often a sniggle is referring to the close relative, co-worker, or passerby, who accidentally knocks over something that was so obviously easily tipped over and should have been easy to avoid. Sniggle is a derogatory term that is often associated with personal descriptions such as annoying, bland, and stinky.

That sniggle keeps drinking from my coffee in the meeting.