Oh My Bad

1. It's a strong emotion or exclamation of acknowledging your shortcoming, fault, or evil done.
2. It's expression of surprise out of wrongly said or done.

oh my bad! I press the wrong key :-(

Oh my badness!

The opposite of oh my goodness. When we have said or done something bad or sinful it is ones badness that had caused one to behave in such a manner.

Oh my badness! I have set the house on Fire.