system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: what are the Panama Papers?
gpt
Oooooh this goes back a bit. 

Basically there was a firm call Mossack-Fonseca that handled the financial affairs of many of the world's wealthiest people (including numerous heads of state and former heads of state). Their job was to basically dodge as much tax as possible. They did this using fancy legal tactics (The details of which may be a bit involved for an ELI5 - but moving money about in ways that make it hard to tax is the gist). This allowed these rich people to pay little or no tax on their earnings or inheritances in some cases. And technically this was all legal (if highly unethical). 

The documents that detailed all this tax dodging were leaked to the press, who, after a lot of hard work to interpret (apparently even the documents made it hard to see from whom the money was coming) published lists of people they had identified and how much money they didn't pay tax on. There were a couple of terabytes of data handed over. Caught up a lot of important people. (Named Panama papers because Mossack Fonseca were based there).