Dark Claw & Lamp (Patreon)

"OK fine... best item I have." He produces a small stone oil lamp... 

"Rumour has it there's a powerful genie in there. But I've had no luck making it work. if you want it, it's yours for the low low price of 100GP." 

DM notes – if you've played a certain fantasy game from long ago, you'll know this trick. Have the players try to work out how to work the lamp. Have them succeed, especially if it's one greedy character you want to punish. Put them up against this demon and laugh hysterically. Or alternatively, have the demon be glad someone has finally let them out.