Someone who You invite then constantly changes plans to not come and or when you do invite them they never agree to come
I invited my friend to come and last min they cancelled, with a lame excuse such a flake.
Or you never agree to do anything you are super flaky.
A flake is someone who generally makes plans with you, promises to do things with or for you but can never seem to follow through. When confronted with their behavior they usually get defensive and run away.
Jisu promised to go out with me. She never showed up. We made plans saturday night and she came up with an excuse why she couldn't show up. Jisu is a flake
Definition: person who does not show up to complete his volunteer activities.
"We were supposed to see each other but he flaked"
An unreliable person; someone who agrees to do something, but never follows through. Usually cancels last second or doesn't show up at all and doesn't answer your calls or texts.
We were all supposed to go clubbing last night but Jaden flaked