I Flaked
This is used primarily by people in Hollwood to explain why they didn't show up at a planned event that they promised to attend.
Arnold: Dude,you promised to come to my private party and bring the cocaine.
Sylvester:Dude, I Flaked.
Arnold:Oh, that's cool.
Sylvester:Dude, I Flaked.
Arnold:Oh, that's cool.