When you do something half-assed or carelessly. Not following through to the fullest extent.

When you are "friends" with someone you work with or go to school with but do not have contact with that person outside of the office/classroom.

A part-time friend is a person who acts like they want be friends with you when you're there but could give a fuck less about you when you aren't physically there.

In other words, someone who wants to be your friend only when it's convenient for them.

Part Time Hooker

A woman who only does prostitution as a part time job.

A non-exclusive relationship. Can involve people being honest and on the level with each other, or cheating on or lying to others.

It can be a positive relationship where people who don't want to be alone, but aren't wanting or able to be in a full-time/exclusive relationship, can have a friend to do activities with. It can be sex based, or include other activities and sharing. It can be more than just a friends with benefits relationship as well.

It can also be a negative relationship, where one is cheating or leading on a partner and avoiding being exclusive. It can be just about sex, it depends on the individuals involved.

someone who is giving a half ass effort, not giving it your all but acting as if you are

Those best friends who decide that it's okay to disappear for months at a time and not speak to you, only to come back as if they never left asking for a favour!