A short not necessarily small, in fact quite rotund and flabby, vindictive person ie ex wife who regrets her previous actions and spends the rest of her sad little (quite literally) life trying her hardest to make everyone elses life a misery.
Thankfully most people see this person for what they really are and treat them as they would something on the bottom of their shoe.

When some little bitchboy is acting like a little tiny pee pee poo poo baby and messing up the group plans.

A selfish, untrustworthy, deeply obnoxious or evil person of diminutive size, whose ostensibly unthreatening appearance allows them to fulfil their predisposition for causing unprovoked pain and suffering in an under-hand manner for anyone who has the misfortune to strike-up a friendship them.

An ex-wife who sends offensive and threatening letters and emails to her former husband and his wife, and has been warned on a number of occassions by the Police for doing so.

A bitter and twisted money-grabbing bitch who cannot let go, and wants to be kept in the lifestyle she wants despite having been divorced years ago.

Aka red dwarf