Shitting in the dark
A metaphor used for when you're committed to a situation but are unsure how it is going to turn out. When you are "shitting in the dark" you have to complete the task whether you know what your doing or not. It may turn out to be messy or it may be a success.
Bob really left me "Shitting in the dark" on this one.
shit in the dark
When you go to take a shit and the light isn't working.
I took a shit in the dark while writing this.