Most illegal businesses in your world?

What is your setting's silk road? Your 'fairy dust' trades? Your secret taverns in the prohibition-era Dwarven kingdom?

*In the Gaian Republic, calling the cuddle-therapy business 'illegal' would be an understatement. It is deemed both heretical and treason to the state for 'turning men soft', making it punishable by death twice over. This means they'll make you watch them slaughter a young lamb genetically engineered to look as 'cute' as possible, then execute you after you've had time to digest what you saw.*

*Despite this, cuddle-therapy is still worth the risk to most people willing to break the law, due to the big-money some are willing to pay for it. Such big-money is spent due to the severe lack of deep connections in Gaia, that most AI partners are unable to fulfill.*