Doing a Giuliani

This is a subtype of doing a solid wherein the favor/task involved is for one reason or another shady either by legality, public perception, or both.

The one who requests a Giuliani and the one who acts out (or attempts) the Giuliani request may have different levels of understanding of exactly how nefarious the deed being done is or what the consequences might be as the Giuliani frequently arises in dont-ask-dont-tell scenarios. All that is necessary to qualify as a Giuliani is that both parties understand that the request is nefarious.

Inmate 1: Dude, can you believe what our boy did to us. He has us out Doing a Giuliani for him no questions asked, and then throws us under the bus as soon as it gets hot.
Inmate 2: Yeah man... Hurts after all these years. So much for loyalty.