Well let's see...
Not sure if it's "shady" but one of my favorites was at this massively expensive restaurant. Super fancy, jacket+tie, and at least $200/person before alcohol. But I'm prepared. Inside my jacket pocket is a case with several pre-loaded syringes for the evening. So during the meal I excuse myself to the restroom, a beautiful marbled room with a chandelier, full cologne counter, etc, so there I am in my finest suit inside this first class restroom with the attendant just outside my stall, shooting up a speedball. Had to then put on my best sober face then go back to the table to struggle to act sober and surprised as my friends had ordered us a $500 bottle of champagne (it was my 21st birthday).
Now on the shadier side... one time I had to meet a dealer in an unfamiliar town; I took the train and he met me at the station. Well after I saw him, I looked around, and didn't see any businesses I could just walk into, the inside part of station itself was closed, and trains only came once every 2 hours so I didn't want to miss my return train coming in 20min by going exploring, and I was sick as fuck anyway. So I just went around to the side of the building, sat down in this little area just barely hidden from the line of sight of the people milling about the platform and the road on the side, and just shot up right there. Was so scared someone was going to wander over and see me. Got it done tho.
Let's see... oh there was the bathroom on the casino cruise, hospital bathrooms, the nasty ass PABT terminal bathroom in NYC. Oh and of course the story I told you all about in the other thread where I crushed up an oxy, added some coke, heated the spoon with a lighter, drew it up, and blasted that speedball---- all while driving between 120 and 150mph on the interstate and flying past cars doing half that. It was going to be way too long until the next rest stop and I needed that hit NOW damnit! So lucky to be alive after that one.