A person that preys on opportunities to "mooch" or benefit from any situation to abstain from personal distress. A person who never drives and always forgets their money. Every situation is a good time to put the comfort of everyone aside and feed off of their misfortune for knowing you.
The person who lives in your building and somehow becomes comfortable enough to invite his/herself over. Sometimes after long days of work you come home to find them eating your food and lounging on your couch playing the N-64 they brought over. "Awesome, your drinking my dr. pepper again, why don't you put this sharpened pencil through your temple you situational mooch."