The best sneaky case is no case at all. You carry your sneaky pete in your hand, assembled or disassembled. Preferably disassembled with butt and ferrule on opposite sides.
The only gear you may need would be a tip tool and your own chalk. Chalk can go in your pocket. Tip tool should be key chain style.
If you're too scared to do this without a case, then your "sneaky" pete is probably too fancy and too expensive and not very sneaky at all.
Flourescent yellow soft McDermott case with "Keith Harry Sacks" written on the case in black Sharpie. That usually gets the attention, and it's so goofy people love and laugh away. I tell them that when I have had too much to drink (if that's possible), it's hard to lose.