Being noisy in public.

Arbitrary surcharges and fees. Like "5% to offset the rising minimum wage" bullshit restaurants are doing.

Alcohol. It's more dangerous than it seems.

Factory farming

Using lies, especially lying about the beliefs of important historical people or of gods in someones religion, for a political campaign is legal

Leveraged buyout, cutting yourself a huge check, folding the company and walking away.

Eh... where? This seems like a very location-specific question.

Stock trading.

I am fine with companies issuing stock and with people selling that stock back to the company. Everything else should be illegal.

capitalism

MlM's. They're predatory.

Alcohol

Rent seeking and usury (the charging of interest)

Those chainsaw discs for angle grinders.

"illegal" is overrated, anyway. Trump did a ton of illegal stuff and yet, here we are.

non-consensual advertising (consensual being things like steam discovery queue, where I actively want to be advertised to), "lobbying" (bribing), fossil fuels and friends, gerrymandering (US), the electoral college (US), publically trading your company

Possibly controversial but prostitution. Allows for regulation and workplace safety. Would probably calm a lot of men down as well and help them focus on the more important aspects of getting into a relationship.

Edit: misread the title and thought it said "legal".

Gambling, overtime working.

Witch hunting.