Fack-Shiggity-Shak - A made-up swear that's so fake, it’s basically a lie, and yo

A made-up swear that's so fake, it’s basically a lie, and you’re just trying to sound cool.

I fack-shiggity-shak’d the teacher when I got a 100 on the test.

He fack-shiggity-shak’d his friends when he spilled soda on them.

She fack-shiggity-shak’d the dog when it ate her homework.