1) When you put your 'shovel' in the 'pit'- often times, an exclamation describing such a situation- honestly, the description is a little amorphous, and is subject to usage on a case-by-case basis.
2) a winning moment
3) whatever you want it to mean...dirty is preferrable
Johnny walks up to Delilah's house and screams:
"Shovel in the Pit!"
"Sure thing, Johnny! Come on in!"
Ladynasty: hey, how's it going?
Tyron: Oh, pretty well
<awkward silence>
Tyron: Shovel in the Pit?
Ladynasty: You know what's good.